A Note About Language
First off, just a critique in the wording of your question; "If so, to what extent? 100% allegorical? 100% realistic? Something in between?" There's no such thing as 50% figurative or 77% literal. Something is either literal or it isn't; there's no 34% literal or anything like that. And the exact same is true for figurative language. (NOTE: I am not saying that something cannot have both a literal and figurative meaning; only that it wouldn't be 50% figurative and 50% literal; it would just be figurative and literal. An expression can have more than one layer of meaning.)
Literal is defined as taking words in their usual or most basic sense without metaphor or allegory. For example, say your sister goes to get ice cream, and you say to your friend, "my sister went to go get ice cream"; that would be a literal expression because it describes the reality that the words themselves explicitly suggest(i.e. that your sister went to go get ice cream).
Figurative is defined as departing from a literal use of words; metaphorical. For example, say your friend is a person who disregards the feelings of others with no guilt or remorse. One might say that he has a "heart of stone"; the expression is metaphorical, not literal, as the expression does not describe the reality that it explicitly suggests(i.e. if you were to cut open into your friend and take out his heart you would find a regular human heart and not one that is made out of stone).
There are many different types of figurative language. In the example above, the type of figurative language being used was metaphor; "heart of stone" was a metaphor for how unsympathetic and callous the attitude of your friend is. But there are other types of figurative language(e.g. simile, hyperbole, metonymy, allusion, idiom, personification, synecdoche, etc.)
What Is Isaiah 14 About?
Verses 1-3 of Isaiah 14 show that Yahweh will deliver the Israelites from their Babylonian captivity and bring them back to their homeland. Starting in verse 4 we see the Israelites taunting the fallen, dead king of Babylon:
Isaiah 14:4-8 You will take up this taunt against the king of Babylon: “How the oppressor has ceased, the insolent fury ceased! 5 The Lord has broken the staff of the wicked, the scepter of rulers, 6 that struck the peoples in wrath with unceasing blows, that ruled the nations in anger with unrelenting persecution. 7 The whole earth is at rest and quiet; they break forth into singing. 8 The cypresses rejoice at you, the cedars of Lebanon, saying, ‘Since you were laid low, no woodcutter comes up against us.’
These verses plainly reveal how persecutive, insolent, and wicked the king of Babylon was to all the peoples and nations that surrounded him. Verses 5-6 show that Yahweh Himself had broken the king’s staff and scepter; in other words, Yahweh's sentence of death brought an end to his tyrannical reign! Hence why all the peoples of the earth who were either oppressed by him or feared his possible threat are now at peace and even celebrating in song(verse 7). Verse 8 even states that the trees the king would regularly cut down would break out in rejoicing! But did these cedars and cypresses literally break out in triumphant jubilation?? Of course not, this is unequivocally figurative language, in particular, personification, which is defined as the attribution of a personal nature or human characteristics to something nonhuman.
God is a master communicator and he uses figurative language here to make a point, i.e. the king of Babylon was so wicked that even inanimate objects would rejoice over his death! Let's continue with the passage;
Isaiah 14:9-11 Sheol beneath is stirred up to meet you when you come;
it rouses the shades to greet you, all who were leaders of the earth; it raises from their thrones all who were kings of the nations. 10 All of them will answer and say to you: ‘You too have become as weak as we! You have become like us!’ 11 Your pomp is brought down to Sheol, the sound of your harps; maggots are laid as a bed beneath you, and worms are your covers.
Sheol is preparing to receive the dead soul of the king of Babylon. The dead are roused to greet the king, including those who were once mighty kings of various nations. Verse 10 shows these dead souls greeting the Babylonian king by informing him that, despite all his former glory and infamous power, he has now become weak like they are, signifying that human distinctions of greatness are meaningless in Sheol, the world of the dead. Are verses 9-11 literal? Did the dead really greet and mock the king of Babylon? Is Sheol capable of being stirred up to meet people, and capable of rousing others? Is the king of Babylon surrounded by maggots and worms in Sheol? Or is figurative language being employed in verses 9-11, just as it is in the verse that directly precedes them(verse 8)?
There are two possibilities here. Either verses 8-11 employ figurative language, OR they are literal. We don't get to pick and choose at whim which parts we think are literal descriptions and which are figurative. Either the immediate context is figurative or literal(of course, it's not impossible that it is both literal and figurative, but there's absolutely nothing in the text to warrant such an interpretation). We don't get to say that one part is literal but the rest is figurative. So, which interpretation is most reasonable? The one that says that verses 8-11 employ figurative language or the one that says that they are literal descriptions of reality? Well, what conclusions would be drawn under each interpretation?
Is Isaiah 14:8-11 Literal?
Isaiah 14:8-11 The cypresses rejoice at you, the cedars of Lebanon, saying, ‘Since you were laid low, no woodcutter comes up against us.’ Sheol beneath is stirred up to meet you when you come; it rouses the shades to greet you, all who were leaders of the earth; it raises from their thrones all who were kings of the nations. 10 All of them will answer and say to you: ‘You too have become as weak as we! You have become like us!’ 11 Your pomp is brought down to Sheol, the sound of your harps; maggots are laid as a bed beneath you, and worms are your covers.
If this passage is a literal description of reality, then we would have to admit that trees are capable of talking/rejoicing. Unfortunately, I have yet to see a tree, any tree, ever talk or rejoice! We would also have to admit that Sheol is capable of being stirred up to meet a person(i.e. the king of Babylon), and that it is capable of "rousing" the dead. Places(or abstract concepts, which is what I believe Sheol is[just as death is]) are not capable of being "stirred up", nor are they capable of meeting people, nor are they capable of "rousing" people. We would also have to admit that the spirits of the dead are capable of greeting, mocking, and speaking, i.e. that they are conscious. Finally, we would have to admit that worms cover the spirits of the dead in Sheol and that maggots are found underneath them; are there corpses in Sheol being decomposed by worms and maggots(that is what worms and maggots do, is it not? They decompose dead bodies[believe me, I've seen it in live-action... NO, not of a human body, that's insane! I've seen them do it to a dead horse])?
But at least the description of Sheol in verses 9-10 is consistent with the depiction of Sheol(Hades) in Luke 16:19-31... Except that it isn't. The only thing that is consistent is that in both cases the spirits of the dead are conscious, but that's where it ends. Nowhere is anyone shown writhing in fiery torment hoping for a mere drop of water for relief. The "shades" do not say, "you too are being relentlessly tormented like us! You too are in pain like us!"; all they say is that the king of Babylon has become weak like them. Pain, fire, and torment are nowhere to be found. Also nowhere to be found is "Abraham's bosom"; nor are two separate compartments of Sheol described. The only thing consistent between Isaiah 14:9-10 and Luke 16:19-31 is the fact that the spirits of the dead are conscious and capable of speaking, but, once again, it ends there.
What If Figurative Language Is Being Employed?
Ok, so far the literal interpretation of Isaiah 14:8-11 isn't particularly optimal. However, what if figurative language is in play? What kind? Well, in verse 8, personification would be in play. The trees are personified; depicted as rejoicing over the death of the Babylonian king in order to make a point, i.e. that the king was incredibly wicked and oppressive towards the "whole earth", such that once he died it could finally be "at rest and quiet"(see verse 7). And in verses 9-10, Sheol and the Rephaim are personified. Sheol is eager to receive the king of Babylon, so much so that it rouses all its dead to mock him and to tell him that he is "weak" just like them. The point of this is to convey the truth that in Sheol ALL are utterly powerless. No one is more significant than another. The king of Babylon, no matter how great and powerful he was while alive, is now weak and insignificant due to being dead; his fate is the same as all the other "leaders of the earth" and "kings of the nations". This greatly resembles what is said in Ecclesiastes 9:2-3.
Ecclesiastes 9:2-3 It is the same for all, since the same event happens to the righteous and the wicked, to the good and the evil, to the clean and the unclean, to him who sacrifices and him who does not sacrifice. As the good one is, so is the sinner, and he who swears is as he who shuns an oath. 3 This is an evil in all that is done under the sun, that the same event happens to all. Also, the hearts of the children of man are full of evil, and madness is in their hearts while they live, and after that they go to the dead.
There is no discrimination when it comes to death; not even between the righteous and the wicked(compare this to Luke 16:19-31 where Lazarus[who the story never says is even a righteous man in the first place! Merely that he "received bad things" in life{Luke 16:25}!] is carried by the angels to the bosom of Abraham... What an absurd story!). The author of Ecclesiastes himself says that this "is an evil in all that is done under the sun"; that doesn't change the fact that it's true(just as it's true that righteous people many times experience horrifying things). The point is, Sheol and the Rephaim are personified to convey the message that the king of Babylon has been brought to nothing; Sheol was not literally excited to meet the king, nor were the Raphaim literally mocking the king. It's figurative language!
And finally, verse 11. The pomp, splendor, and magnificence of the king of Babylon is brought down to Sheol, and so too the sound of his harps. Does this mean that the king retains his pomp and the sound of his harps? The verse doesn't actually say that anything happens to the splendor(or music of the harps) of the king of Babylon; simply that it is "brought down to Sheol". Well, if Sheol is a place of nonexistence, then the pomp of the king being brought down to Sheol would mean that his pomp is reduced to nothing! And the same goes for the music of his harps. The king does not retain the music or his splendor; they are reduced to nothing, just as he is. This image of being nothing is hammered down by the end of verse 11, where "maggots are laid as a bed" beneath the king of Babylon, and where "worms are his covers". This is incontrovertibly imagery pertaining to the grave, more specifically, dead bodies/corpses. Just as a corpse lays in the grave silent and lifeless, rotting and destroyed by worms and maggots, so was the fate of the king of Babylon; to lay in Sheol, "rotting" and utterly destroyed by God(verses 5-6), henceforth silent and lifeless. All this is corroborated by what Isaiah says elsewhere.
Isaiah 26:14 The dead will not live, the departed spirits[רְפָאִים] will not rise; Therefore You have punished and destroyed them, And You have eliminated all remembrance of them.
The "other lords" who have had dominion over Judah(verse 13) have been punished with destruction, hence the Rephaim(spirits of the dead... the same things being talked about in Isaiah 14:9) will NOT rise(cf. Psalm 88:10); they are incapable due to being destroyed by God.
Isaiah 38:17 Surely for my own welfare I had such great anguish; but Your love has delivered me from the pit of oblivion, for You have cast all my sins behind Your back.
Death is a "pit of oblivion" because dead souls are senseless and unconscious(just as a rotting corpse with "maggots beneath" it and "worms as its covers" is). That is the point being made by God drawing a parallel between the state of the king in Sheol and the state of a corpse in the grave. The lifeless and destroyed state of a rotting corpse in the grave is analogous to the lifeless and destroyed state of the king of Babylon in Sheol; a metaphor(another type of figurative language) is being used in verse 11.
I want to consider an objection to the figurative interpretation of Isaiah 14:8-11. The following quote is taken from @SpiritRealmInvestigator's answer.
"If all chiefs on earth and all kings of nations are in a state of non-being, then their characterization as "weak" and the humiliation experienced by the king of Babylon upon entrance to Sheol would be hard to make sense of. If both righteous and wicked become non-existent upon death, then everyone is equally strong and equally weak, and equally unconscious. There would be thus no opportunity for the king of Babylon to feel ashamed about the meaninglessness of his past earthly glory if he becomes unconscious and non-existent at death. Likewise, there would be no opportunity for previous kings to "welcome" the newly arrived king of Babylon if they are all in a state of non-existence."
Well, first of all, that the righteous and wicked are equal in death is a fact. I'm not saying that it is good... It is unquestionably "an evil done under the sun". But it IS still a fact. Ecclesiastes 9:2-3 affirms this. Second of all, where does it say that the king of Babylon NEEDS to experience humiliation? But either way, it would not matter. To ancient middle eastern people, one need not know about their humiliation in order to be humiliated. What mattered was how other people viewed something, not only how the person being humiliated views it. For example, not being given a proper burial was the deepest degradation to ancient middle eastern people. Consider;
Ecclesiastes 6:3-5 If a man fathers a hundred children and lives many years, however many they may be, but his soul is not satisfied with good things and he does not have a proper burial, then I say, “Better the miscarriage than he, 4 for a miscarriage comes in futility and goes into darkness; and its name is covered in darkness. 5 It has not even seen the sun nor does it know it; yet it is better off than that man.
Yikes! Is a man who had a tremendously fulfilling life but didn't get a proper burial REALLY better off than a miscarriage?? Well, you see, it didn't matter to ancient eastern people whether the reality was that the man was not actually worse off than a miscarriage. That's the point; it didn't matter greatly to people whether the person not being given a proper burial was conscious of the fact; to them, it is an enormous humiliation no matter what! Humiliation did not depend on what the person feeling the humiliation viewed it as; if the people viewed something as humiliation, that's what mattered(e.g. not being given a proper burial is the worst of all humiliation. That did not depend on whether or not the person not being given a proper burial was aware of the fact). So, the argument given by @SpiritRealmInvestigator is not convincing.
Addendum - Rebuttal
Hello. I had already made a rebuttal a few months back, but I lost it all (along with other stuff) in an unfortunate incident. However, I'm rewriting it, not because I think this is important at all, or because I want to win a debate, but because I feel like writing something... :-)
A user named @SpiritRealmInvestigator said:
"This is a false dichotomy."
This is accurate. Any time someone gives you two options A or B they are setting up a false dichotomy; a real dichotomy is A or ~A. However, to be sure, a false dichotomy is not false because the options being dichotomized are invalid; it's false because it's based on a premise that limits what options are available by leaving no room for a third or fourth option that could be correct. However, that's where it stops. The fact that I set up a false dichotomy does not mean the options I provided are invalid, or that another option is instead valid, or even that the two options I provided are not the only valid ones! I'm not saying that he is saying any of these things. I just want to make sure everyone's on the same page. Moving on, the same user said:
"Rajesh is proposing an unwarranted dichotomy that can easily be shown to be false via reductio ad absurdum. First of all, if a narrative includes some elements which are completely fictitious (e.g. superman, thundercats) or real but with some tweaks (e.g. trees that can speak, where speaking is real and trees are real but the combination is not), it doesn't follow that ALL elements of the narrative are fictitious. In fact, if we concede Rajesh's false dichotomy that we cannot pick and choose what is real and what is not, then we would be forced to consider either everything as real or everything as figurative. Therefore, if we entertain the case in which everything is figurative, this would lead to obvious absurdities, such as:"
And then he goes on to list a bunch of stuff from the passages. Anyway, his reductio ad absurdum did not work as he was very plainly strawmanning my arguments (honestly, did he even read what I said?). He says that "it doesn't follow that ALL elements of the narrative are fictitious". I agree, but I didn't mention elements anywhere. I only mentioned descriptions. This is what the user was responding to:
There are two possibilities here. Either verses 8-11 employ figurative language, OR they are literal. We don't get to pick and choose at whim which parts we think are literal descriptions and which are figurative... So, which interpretation is most reasonable? The one that says that verses 8-11 employ figurative language or the one that says that they are literal descriptions of reality?
Notice I said "descriptions" and not "elements". I don't mention elements anywhere. I was talking about literal and figurative descriptions. He must also not have read what I wrote regarding figurative and literal language at the beginning of my answer. "Your friend has a heart of stone" is figurative language, not literal, and yet, I am not denying the existence of your friend, nor the existence of stones, nor the existence of hearts; I'm denying the existence of a human being that is capable of living with a heart that is made out of stone. It's the entire expression that is figurative; not each particular element/word. So, his reduction ad absurdum fails due to the fact that he strawmanned my arguments.
The user goes on to say:
"Given that this position is obviously absurd, by reductio ad absurdum we conclude that the narrative is more complex than Rajesh makes it out to be, and a simplistic "either everything is real or everything is fictitious" treatment of the passage is not the appropriate approach."
Notice that nowhere in my entire answer do I say that "either everything is real or everything is fictitious". This is a patent misconstruction of my argument. Then he says:
"Thus, it is entirely possible for the presence of the Rephaim in Sheol to be one of those elements in the narrative which Isaiah believed to be grounded in reality."
I agree. The Rephaim are depicted as real in multiple places in the Bible (e.g. Job 26:5, Psalm 88:10, Proverbs 2:18; 9:18, Isaiah 26:19). I'm not denying the existence of the Rephaim. I'm denying that Isaiah is proving a literal description of Rephaim in v.10. My interpretation that Isaiah 14:10 employs figurative language is entirely sound. How so? Because the immediate context clearly evokes figurative language. What justification is there for saying that Isaiah 14:10 in particular is literal while everything around it is figurative? I suppose a "basis" is provided in what the user says next:
"In fact, we know from prior sources such as Number 16 and 1 Samuel 28 that both the belief in Sheol and the belief in conscious disembodied spirits already existed prior to Isaiah's generation. So it is not unreasonable to think that Isaiah was familiar with these concepts, and validated them through their inclusion in this chapter"
Is a passage written 300 years prior to the events detailed in Isaiah (i.e. 1 Samuel 28) + a passage that (I've said this already) does not support the belief in conscious disembodied spirits in Sheol (i.e. Numbers 16) really @SpiritRealmInvestigator's justification for Isaiah being literal in verse 10? His logic is tantamount to, "the notion existed, therefore Isaiah supported it". I really hope I don't have to point out how fallacious that logic is. As I said already, we have no reason to think that Isaiah was being literal in v.10 and every reason to think that he was being figurative, namely, that the immediate context is unequivocally figurative. The only reason he concludes that Isaiah must be speaking literally in v.10 is that he is heavily biased toward his preconceived notion that the spirits of the dead are conscious and capable of interactions, since the possibility that Isaiah is speaking literally in this verse would fit perfectly with that preconceived notion. This is what I mean by "pick and choose at whim". This is not exegetically valid whatsoever.
More Stuff:
@SpiritRealmInvestigator has written another rebuttal. He writes:
"This is an ambiguous distinction, and the rebuttal still holds even if the ambiguous distinction is conceded. My rebuttal still holds even if we grant Rajesh's distinction between "elements" and "descriptions" (although he doesn't provide a clear-cut manner to distinguish between the two, so the distinction is at best ambiguous, and at worst, arbitrary or non-existent)."
He says that my distinction is "at best ambigious, and at worst, arbitrary or non-existent". To this, I implore him once more to look at the example I included at the onset of my post since he still does not understand how figurative language works. "Your friend has a heart of stone" is figurative language, not literal, and yet, I am not denying the existence of your friend, nor the existence of stones, nor the existence of hearts; I'm denying the existence of a human being that is capable of living with a heart that is made out of stone. The elements in the sentence "your friend has a heart of stone" are your friend, hearts, and stones; however, the description of your friend is that he has a heart of stone. Do you see the distinction between the elements and the description itself? Once again, I am not denying the existence of the elements [friend, heart, stone], but the reality that the description explicitly portrays [that your friend has a heart of stone]. This is not at all an "ambigious distinction". He then says:
"For the sake of argument, if we concede Rajesh's adamant suggestion that we can't pick and choose which descriptions are figurative and which descriptions are literal, then it would follow that either all descriptions must be regarded as fictitious or all descriptions must be regarded as realistic."
He then proceeds to cite verses 22-23, not realizing that my argument is only regarding the immediate context, not the entire chapter. The immediate context of Isaiah 14:10 is figurative language. Verse 22-23 are not part of the immediate context of verse 10. What follows is technically a strawman of my argument, though I can't blame him since I did make it sound as though I was arguing in this manner:
"Here God is described as delivering a message. Since we can't pick and choose descriptions, should we conclude that God is incapable of delivering messages ???"
Again, I'm talking only about the immediate context, but you're right that that conclusion is a non-sequitur. But my argument isn't, "Isaiah is employing figurative language in verse 10, therefore the Rephaim are incapable of talking and mocking." My argument is, "Isaiah is employing figurative language in verse 10, therefore his description of the Rephaim talking and mocking is not a literal description". I'm not trying to make a case for Christian mortalism; I'm only trying to neutralize this text, that is, make it compatible with either the belief that the dead are conscious or the belief that they are unconscious. He then cites verse 5-6 of Isaiah 14, and proceeds to say:
"There are several descriptions here: God breaks the staff of the wicked, the scepter of the rulers. Should we conclude that God cannot do this in real life ??? Wicked and rulers are described as ruling the nations in anger with unrelenting persecution. Should we conclude then that rulers cannot rule nations?... Should we conveniently regard the parts that we think are realistic as "elements" and the parts that we think are figurative as "descriptions"?"
Again, this is a strawman. I'm not concluding that the Rephaim cannot speak and greet from Isaiah 14:10; I'm concluding that there is no reason to think that Isaiah is speaking literally here, and that therefore Rephaim can speak and greet. I'm not making a case for Christian mortalism here. And he continues to do the same thing with verses 11 and 14. That's all for now...
Even More Stuff Apparently:
@SpiritRealmInvestigator has said:
"Rajesh provided an example, but an example is not a formal definition. What counts as an "element" and what counts as a "description" is ambiguously left open to interpretation. My best guess would be that Rajesh considers "nouns" and "pronouns" to be "elements" and any other syntactical structure (that includes a "noun" or "pronoun") to be a description ??"
How about we just take a look at the dictionary definition of "description" (it shouldn't take a genius to think of this)? Oxford Languages defines "description" as a spoken or written representation or account of a person, object, or event. Merriam-Webster defines "description" as a statement or account giving the characteristics of someone or something: a descriptive statement or account. Essentially, a description is a written/spoken account of someone or something (such as an object or an event). "Your friend has a heart of stone" is a description because it details something about your friend, namely, that he has a heart of stone. Moving on, he says:
"If so, then the following sentence should fit the (non-specified) definition of "description"... Notice that this sentence comes from the immediate context, and has multiple nouns/pronouns: [all, who, leaders, earth]. It would be hard to argue that this description is allegorical/unrealistic (or are we going to say it is unrealistic to talk about "the leaders of the earth"?), and yet this is mentioned in the immediate context of the Rephaim."
First of all, I'm not sure where he is getting the terms "unrealistic" or "fictional" from; I don't use them anywhere in my post. Second of all, "all who were leaders of the earth" is not a description; it's a clause that is part of a description. The description is the entirety of verse 9 (which @SpiritRealmInvestigator conveniently leaves out).
[Isaiah 14:9] Sheol beneath is stirred up to meet you when you come; it rouses the shades to greet you, all who were leaders of the earth; it raises from their thrones all who were kings of the nations.
So, what is happening here? What is v.9 a description of? Why, of Sheol! Sheol is described as being stirred up to meet the king of Babylon and is described as rousing the shades and all who were leaders of the earth to greet the king. That's the description. Now, is this description figurative? Yes, because Sheol is not a conscious entity capable of rousing and being stirred up. My original point stands.
"Therefore, it is not unreasonable to think that the description of the Rephaim as conscious in Sheol (verses 9-11) is one of those descriptions that are realistic, just like God is realistically described as conscious and able to deliver messages in verses 5-6 and 22-23"
Again, where are terms like "realistic" coming from? All I'm saying is that we have no reason to think that the description of the Rephaim in v.10 is literal.
So, in conclusion, the context of Isaiah 14:10 is clearly figurative language; it is not a literal depiction of reality. In verses 8-10, personification is employed(personification of trees, Sheol, and dead spirits). In verse 11, metaphor is employed(by attributing characteristics of dead bodies and the grave to dead souls and Sheol). As @Dottard said in his answer, "nothing can be deduced about the consciousness or otherwise of the dead."
Have a good day! Hope this helps. :)