We read Genesis One, verse one and we see that the fundamental reality of Scripture is that "In the Beginning God created the heavens and the earth."
So is this the "creation theory"?
The work of day two is not a theory. It is a revelation from God in the infallible inspired Scripture. The scholarship and expertise in the Hebrew Language articulated by Dr. John C. Whitcomb has never been "debunked," nor has it ever been disproved. Canopy Theories are theories but what is described in Genesis One, verse one is not a theory. Likewise, what is described in Genesis One, verses 6-8 is not a theory.
...Like the man who said, "I see land!", in the case in which this was true.
But, nah. land is a theory. LOL
I'm not the most ardent potential/former supporter of the Canopy interpretation of Genesis 1:6-8.
But I see your point. Something is true here.
...As for the Hebrew, I figure that it is the most life- and terra-centric conceptual scheme possible for humans. Genesis 1 is not written in an alterate lexicon for modern English conceptual schemes.
So I can't help but wonder exactly how Adam and Eve linguistically conceived of the atmosphere and that particular subject's linguistic relation to 'hassamayim' (vv. 1 and 9, and 14, 15, and 17; but not v. 8) and the luminaries.
Here on land we say 'he's under the ocean', meaning under its surface. This is obviously because we do not live 'under' the ocean: we do not breathe water instead of air.
Of course we breathe the air: that which is that stuff above us, even where are the Weather Class clouds.
But we do not live in 'cloud cities', as opposed to on (really, really, on) the ground.
So the water that is 'above' the expanse need not be likened to a clearly specious or term-obsessed use of 'below' or 'under' the ocean. The issue, here, is that between
(a) life-indifferent grammar, such as an all-purpose gravity-based mechanical engineering, or even celestial robotics,
(b) life-centric grammar.
The latter grammar allows for a global version of life-centrism, and this is what I think best fits that of the Hebrew data of Genesis 1:1-18. After all, God does not create only land fauna and land flora. He creates even those of the water as well, and these first:
Presumably He creates all flora first. Both land- and water-bound; peach trees and bladder rack, mangroves and sea-bottom plants. And presumably He creates flora in the same chronological order as he does the fauna: water-bound kinds first: kelp before mangroves (perhaps assuming that the seemingly water-bound mangrove species of today were not water-bound species to begin with?).
So the Genesis 1 account of Creation Week is looking at the entire globe in terms of life(-support), not merely nor mainly to that of land. Thus, the main point of vs. 9-10 is not for land to be distinguished from the water, but, rather, for the twain to be established in relation to one another for the benefit of the whole.
I think the simple sense of meaning for the work of day two is that God by His power took some of the water and raised it up above the surface of the planet to make what we call the atmosphere - an expanse or space between the waters above and the waters beneath.
simple, direct, and comprehensible by a two-day old Adam, or by a 5-year old Abel and Cain.
Location, location, location.
By way of analogy to the debates over the whole account, I recommend Brinker's interview of Tom Gegax:
youtube, three audio-only videos: