The Roman Imperator was able to force his will on Rome because, in the Roman Imperial cult the Imperator was divinely selected by the gods of Rome and through apotheosis they and their families would become gods (divus) upon their deaths.
Another element in the Roman state religion was what is generally referred to as the imperial cult. This cult regarded emperors and members of their families as gods.
Another element in the Roman state religion was what is generally referred to as the imperial cult. This cult regarded emperors and members of their families as gods. On his death, Julius Caesar was officially recognised as a god, the Divine ('Divus') Julius, by the Roman state. And in 29 BC Caesar's adopted son, the first Roman emperor Augustus, allowed the culturally Greek cities of Asia Minor to set up temples to him. This was really the first manifestation of Roman emperor-worship. While worship of a living emperor was culturally acceptable in some parts of the empire, in Rome itself and in Italy it was not. There an emperor was usually declared a 'divus' only on his death, and was subsequently worshipped (especially on anniversaries, like that of his accession) with sacrifice like any other gods...
So while the Roman Imperators were too bashful to declare themselves to be gods ("divus") while living, they were honored as gods after their death, maintaining national loyalty.
So to declare the Jewish Messiah to be the son of God, Lord, etc. was a revolutionary act, putting the risen Messiah in dangerous competition with the Imperators.
It has already been pointed out that Koine lexica identify multiple ways that KURIOS is used, even within the NT, so we must immediately dispense with the notion that the word, "by definition", means "YHVH". That's patently false and I won't address that further here except to point to this example which I don't think has been raised yet:
[Jhn 4:19 KJV] 19 The woman saith unto him, Sir [IE: KURIOS], I perceive that thou art a prophet.
She would not have said "YHVH, I can tell you are a prophet" as that would make no sense.
If we look at the context Paul is discussing the "manifestations of the spirit/breath of God":
[1Co 12:1 DBY] But concerning spiritual [manifestations], brethren, I do not wish you to be ignorant.
He reminds them how before they were rescued they were "so open minded that their brains would fall out" (like the "Funny Mentalists" that ape the spiritual manifestations given in the last days of the Jewish covenants to divinely endorse the apostles). IE: prophecies that don't come true, healings that require pretending you don't have symptoms, "tongues" that are gibberish, etc. They would ignorantly be led in paths of darkness by the spirit that is operating still among the disobedient:
[1Co 12:2 DBY] Ye know that when ye were [of the] nations [ye were] led away to dumb idols, in whatever way ye might be led.
[Eph 2:1-3 DBY] 1 and you, being dead in your offences and sins -- 2 in which ye once walked according to the age of this world, according to the ruler of the authority of the air, the spirit who now works in the sons of disobedience: 3 among whom we also all once had our conversation in the lusts of our flesh, doing what the flesh and the thoughts willed to do, and were children, by nature, of wrath, even as the rest:
Or rather, "...according to the ruler of the authority of the air of the breath that now operates in the disobedient...".
[1Co 12:3 DBY] I give you therefore to know, that no one, speaking in [the power of the] Spirit of God, says, Curse [on] Jesus; and no one can say, Lord Jesus, unless in [the power of the] Holy Spirit.
So Paul is "giving them to know" that if anyone professes to be a prophet speaking as a manifestation of the breath of God and their "prophecy" says that Jesus is or should be under YHVH's "ban" then they are not truly speaking by the breath of God but rather by the breath of the ruler of the KOSMOU (which I tentatively take to be either the high priest (as the ) or the Satan - probably the high priest who acted as and under the control of the Satan). The "ban" is the curse that God promised would fall on those who did not return to the God of their fathers (Abraham, Isaac and Jakob) but instead rejected their Messiah:
[Mal 4:4-6 NASB] 4 "Remember the law of Moses My servant, even the statutes and ordinances which I commanded him in Horeb for all Israel. 5 "Behold, I am going to send you Elijah the prophet before the coming of the great and terrible day of the LORD. 6 "He will restore the hearts of the fathers to their children and the hearts of the children to their fathers [IE: "Abraham, Isaac..."], so that I will not come and smite the land with a curse."
It was not enough to be physically descended from Abraham; they had to be "of the faith of Abraham":
[Mat 3:7, 9 ASV] 7 But when he saw many of the Pharisees and Sadducees coming to his baptism, he said unto them, Ye offspring of vipers, who warned you to flee from the wrath to come? ... 9 and think not to say within yourselves, We have Abraham to our father: for I say unto you, that God is able of these stones to raise up children unto Abraham.
[Rom 4:11 ASV] 11 and he received the sign of circumcision, a seal of the righteousness of the faith which he had while he was in uncircumcision: that he might be the father of all them that believe, though they be in uncircumcision, that righteousness might be reckoned unto them;
So that is the prevailing context of our verse. So in this context, what does KURIOS mean?
IF it refers to the title that Jesus received because of his obedience to God to such a degree that he went all the way to his death at the "hands" of the Jews via Pilate:
[Phl 2:8-11 ASV] 8 and being found in fashion as a man, he humbled himself, becoming obedient [IE: to God] even unto death, yea, the death of the cross. 9 Wherefore also God highly exalted him, and gave unto him the name [IE: the "title"] which is above every name [IE: the "title"]; 10 that in the name [IE: the "title"] of Jesus every knee should bow, of things in heaven and things on earth and things under the earth, 11 and that every tongue should confess that Jesus Christ is Lord, to the glory of God the Father.
IF it refers to the title "YHVH" then it still says that God "gave him the title":
[Exo 23:21 ASV] 21 Take ye heed before him, and hearken unto his voice; provoke him not; for he will not pardon your transgression: for my name is in him.
[1Ki 9:3 ASV] 3 And Jehovah said unto him, I have heard thy prayer and thy supplication, that thou hast made before me: I have hallowed this house, which thou hast built, to put my name there for ever; and mine eyes and my heart shall be there perpetually.
[1Ki 11:36 ASV] 36 And unto his son will I give one tribe, that David my servant may have a lamp alway before me in Jerusalem, the city which I have chosen me to put my name there.
[2Ki 21:7 ASV] 7 And he set the graven image of Asherah, that he had made, in the house of which Jehovah said to David and to Solomon his son, In this house, and in Jerusalem, which I have chosen out of all the tribes of Israel, will I put my name for ever;
[2Ch 33:7 ASV] 7 And he set the graven image of the idol, which he had made, in the house of God, of which God said to David and to Solomon his son, In this house, and in Jerusalem, which I have chosen out of all the tribes of Israel, will I put my name for ever:
So what does that mean? That means that when David sat down in his throne he was sitting on YHVH's throne:
[1Ki 1:17 ASV] 17 And she said unto him, My lord, thou swarest by Jehovah thy God unto thy handmaid, saying, Assuredly Solomon thy son shall reign after me, and he shall sit upon my throne.
[1Ki 1:30 ASV] 30 verily as I sware unto thee by Jehovah, the God of Israel, saying, Assuredly **Solomon thy son shall reign after me, and he shall sit upon my throne in my stead; verily so will I do this day.
And so on...
Solomon, because he sat in YHVH's throne (and wielded his scepter) the God of Israel presided through Solomon. Hence, Psalm 45 addresses Solomon:
[Psa 45:6 ASV] 6 Thy throne, O God, is for ever and ever: A sceptre of equity is the sceptre of thy kingdom.
Solomon is a type of "the Ruler of Peace" (IE: the Messiah):
[Rev 3:21 KJV] 21 To him that overcometh will I grant to sit with me in my throne, even as I also overcame, and am set down with my Father in his throne.
So no matter how you slice it Jesus is only KURIOS to the degree that he draws his authority from his God and Father:
[Jhn 5:43 KJV] 43 I am come in my Father's name, and ye receive me not: if another shall come in his own name, him ye will receive.
KURIOS is above every other title that is applied legitimately to men but he answers to HIS God, which is also the one who begat him.
[2Co 11:31 KJV] 31 The God and Father of our Lord [KURIOS] Jesus Christ, which is blessed for evermore, knoweth that I lie not.
[Eph 1:3 KJV] 3 Blessed be the God and Father of our Lord [KURIOS] Jesus Christ, who hath blessed us with all spiritual blessings in heavenly places in Christ:
[1Pe 1:3 KJV] 3 Blessed be the God and Father of our Lord [KURIOS] Jesus Christ, which according to his abundant mercy hath begotten us again unto a lively hope by the resurrection of Jesus Christ from the dead,
[1Co 11:3 KJV] 3 But I would have you know, that the head of every man is Christ; and the head of the woman is the man; and the head of Christ is God.