That's an interesting take. I would say that the 'immanence' of God in Genesis 2-3 is more apparent than real. He appears as a personal deity, rather than immanent in the panentheist sense, but the story still takes place in the spiritual (heavenly) realm.

The two stories of creation are considered to be different by scholars, but that may be based on misunderstandings. I think it's possible to reconcile them.

I would be interested to know what sources you have for the history. I agree with you about chapter 1 and the flood. According to my understanding, however, the Garden of Eden story also comes from the Babylonian period. It is based, with some editing, on an earlier Sumerian story/myth. As circumstantial evidence, it's interesting that, even though it appears as the foundational story for Judaism and therefore Christianity at the start of the Bible, I believe it's never referred to again in the Old Testament, which suggests that it's a late addition. The other writers don't seem to be aware of it.