Amateur Rocket Hits the Dome of the Firmament

The Mesopotamian cosmos can be understood as multiple planes of existence, layered above one another. The highest plane of existence was heaven, which was the home of the sky god Anu. Below heaven was the atmosphere which ranged from the bottom of heaven (or the lowermost firmament) to the ground that humans walk on. This region between heaven and earth was inhabited by Enlil, the king of the gods in Sumerian mythology. Below the ground was the cosmic ocean, and this was believed to be the place of residence of the sibling deities Enki and Ninhursag. The lowest plane of existence was the underworld. Other deities inhabited these planes of existence even if they did not reign over them, such as the sun and moon gods.In later Babylonian accounts, the god Marduk alone ascends to the top rank of the pantheon and rules over all domains of the cosmos.The three-tiered cosmos (sky-earth-underworld) is found in Egyptian artwork on coffin lids and burial chambers.

The Sumerian cosmogonic and creation myths trace the origin of the universe to the primeval sea. This was the first form of being. The primeval sea begot heaven and earth, gods conceived in human form and united in a cosmic mountain. Heaven (An) the male and earth (Ki) the female then begot the air god (Enlil) who separated heaven from earth and carried off his mother Ki. Following this, man was created and civilization established.
Later, the Babylonians and Assyrians (who unlike the Sumerians spoke a Semitic language, Akkadian, and are often lumped together as "Akkadians") reworked ideas derived from the Sumerian myths into a version of their own, which Zeitlin synthesizes thus (p. 4):
In Akkad, too, it is the primordial oceans, Tiamat and Apsu, that exist at the very beginning, long before heaven and earth are created. Then several generations of gods are born, including Ea, the god of wisdom. Apsu and Tiamat are so distressed by the continued clamour of the deities that Apsu decides to destroy them. Ea, however, succeeds in preventing this by killing Apsu with the aid of a magical incantation. Ea's wife then gives birth to Marduk, a great god who soon demonstrates his courage. He kills Tiamat who with the assistance of renegade gods and vicious monsters, had been bent on avenging the death of her husband. Splitting Tiamat in two, Marduk then proceeds to create heaven and earth from her huge corpse. Following this, Marduk with the co-operation of his father Ea creates mankind from the blood of the rebel god Kingu, who had led Tiamat's hostile host.
Speiser (p. 8 and ff.) insists, and I agree, that the question of most interest in the present context is not whether the statement of how creation happened is true or false, but rather what it means, and specifically: what it meant to the writer and the audience and how the account came to take the form it took. The Babylonian creation epic, now called the Enūma Eliš, which is usually considered the "standard" Mesopotamian version, not only agrees with Genesis in many of the points that it describes (such as the creation of light, the firmament, etc. etc.) but most tellingly it places them in the same order, suggesting a common origin. This, Speiser says, is hardly likely to be just a coincidence. Furthermore, he points out that today nobody seriously doubts this: "The relationship is duly recognized by all informed students, no matter how orthodox their personal beliefs may be."

Quoting from Heidel's The Babylonian Genesis, Speiser tabulates the overall sequence of steps in creation given in the Enūma Eliš as follows:
Divine spirit and cosmic matter are coexistent and coeternal
Primeval chaos; Ti'amat (= t'hom?) enveloped in darkness
Light emanating from the gods
The creation of the firmament
The creation of dry land
The creation of luminaries
The creation of man
The gods rest and celebrate
Now, what does it "mean" that the G