The question is, 'Why did God give words for things in Genesis 1?'
The full answer is not that God, and not man, rules over the day, night, sky, land, and seas. For, such an answer does not explain why God did not give words for plants, light, water, the planet Earth of v. 1, or the light bearers of Day Four.
I think the full answer has to do with the water cycle:
The ANE pagan stories tend to present their deities as obsessively favoring power and will, even violently. Those stories tend to justify the vindictiveness and tyranny of their deities and political leaders. Genesis 1 is radically unlike this. It affirms the Creator purely in terms of life-benevolent values and sensibilities of the Natural Order. Specifically, it affirms humans' everyday values for life and the ecological Earth. Genesis 1 presupposes God's unique transcendence. And it implies that the main way in which God shows to us that He exists, and that He loves us, is by His having designed all natural things such that those things meet our natural needs for things outside ourselves. That design is what often is called 'Divine' Design. But the term 'divine', in this case, is not simply the idea of something which is 'from God'. It specifically is of something which, by its design, affirms our creaturely needs for things 'outside' ourselves. Each atom of our bodies have natural need of things outside themselves. And, everything together which we physically are is a being which has natural need of things outside that being. All that boils down to our having a natural need centrally for the ecological Earth, specifically for a planet which, to begin with, has a water cycle (Proverbs 12:10).
The concern in Genesis 1 specifically for the water cycle can be seen in the five names the account reports that God gives to as many things (vv. 5, 8, 10).
Factor 1: binary cyclically distributed thermal regulation ( 'day' and 'night', v. 4-5 );
Factor 2: radiologically mediative atmosphere ( 'shamayim', (NOT ha-shamayim) vs. 6-8 );
Factor 3: binary thermal surface distribution system ( 'land' and 'seas', vs. 9-10 )
This proposed affirmation of the water cycle can be likened to a list which gives the basic parts of a woman, as such, but does not mention the word 'woman'. If only we recognize that it is a list about a woman, we shall not need to have the word 'woman' spelled out for us. Adam's naming woman was not from God tell Adam what to name her. Rather, Adam recognized her as a woman. Genesis 1 has God naming something's basic parts, and we are to recognize that thing is by its parts. God simply points out those parts to us, by His naming them here. The possibility that this is what God intends is further suggested by what God calls 'good':
What God calls 'good' throughout Genesis 1 has to do with the ecological Earth, not with something else instead
Genesis 1 includes several reports according to which God calls things 'good'. There is at least one such report within each Creation Day's portion except that of Day Two. In the Day Two portion, there is no report of 'good'.
It commonly is assumed that is to the actual work of a given Creation Day that God calls 'good'. So, it commonly is assumed that, since there is no report of 'good' within the Day Two portion, the work of Day Two is being ignored in terms of goodness. Many theologians rightly reject this assumption, but they do not go far enough in affirming what the text affirms for the work of Day Two. They see only what the text spells out, like the list of the parts of a woman.
The land and sea of the first half of Day Three easily is not alone that which God calls 'good' at that point of Day Three. For, the land and the sea are mere subsystems of the Earth's water cycle, and so is the atmosphere (Day Two). It is only upon the establishment of land and sea that the account's possible concern for the physical factors of the water cycle is completed.
The reason the 'light' of v. 3 is called 'good' may be because the 'light' is not part of the physical Earth. For, there is no report of 'good' associated directly for 'the heaven' or 'the Earth' of v. 1, nor for 'the deep' of v. 2, nor for the 'day' and 'night' of vs. 4-5. After God calls the 'light' of v. 3, 'good', the next time the account reports that God calls something 'good', this is in the first part of Day Three. This is when, regardless of the reading, the physical water cycle would have been completed by the establishment of the binary thermal surface exchange function of land and seas.
So, that which God calls 'good' on the first half of Day Three seems to be a combination of the five (or three) factors mentioned above. After all, Genesis 1 is mainly about an actual process, miraculous as it was, of creating and assembling the actual ecology of the actual Earth. The account is NOT to be seen as a mere list of 'items'.
In fact, if Genesis 1 were about only distinct items, then the work of Day Two could not legitimately be held to be even part of the 'good' of the land and sea on Day Three. In fact, to effectively reduce the account to a mere list of 'items' would mean it could just as well be about a process of assembling a cardboard diorama. But the following seven-fold recursion not only is to be seen in the whole completed Creation itself, but in the Genesis 1 account of Creation Week.
The general, (or 'masculine') cosmos and the special (or 'feminine') Earth (Genesis 1:1).
The Earth, as its own general subject, implying that which we all intuit is most valuable about the Earth unto itself in all the cosmos: its abiding maximal abundance of open liquid water (Genesis 1:2).
that water and its special relation to the Sun's light, hence the water cycle (vs. 3-10);
The water cycle and its special beneficiary and member, biology (vs. 11-12);
biology and its special category, animal biology (plant/animal/mineral = animal) (vs. 20-22, 24-25);
Animal biology and its special category, human (vs. 26-28);
The general man and the special woman (Genesis 2:21-23).
