There is no way of really knowing, it is interesting to note however that Ancient people’s likely did not take their cosmology as literal truth, the Israelites were likely no different. As John Walton has said, the Egyptians personified the areas of the cosmos as deities, but this did not mean that they could throw a stone and hit the sky goddess, for example. Likewise, Wayne Horowitz notes;
The current evidence simply does not allow us to know, for instance, if ancient readers of Gilgamesh really believed that they too could have visited Utnapishtim by sailing across the cosmic sea and “the waters of death”; or if a few, many, most, or all ancient readers understood the topographical material in Gilg. IX-X in metaphysical or mystical terms.
It is my personal interpretation that Genesis 1 speaks of the functional origins of the cosmos, not the material origins. Since Ancient Cosmology was primarily function oriented, I feel as though the Earliest readers of Genesis probably did not see this as the literal account of how the world came to be. Rather they understood it in functional terms. An objection I often see however by YECs is that the Wayyiqutol structure of Genesis indicates it was meant to be understood of as real history.
Because seven is a sacred number all across the world, for the simple reason that there are seven visible wandering stars. It shares a common origin with the seven days of Genesis most likely, but is not derived from it. The Babylonians were the first to invent a seven day week.
Ever stop to wonder why 7 is sacred? Seven is God’s number as well. All through scripture we see 7, and God was before all the civilizations you mentioned
The bible is scripture (God’s word) John 1 “1 In the beginning was the Word, and the Word was with God, and the Word was God. 2 He was in the beginning with God.” Scripture has always been here, my friend