The clay Tablets of Sumer were written way before there was a bible or even Jews. At least a thousand years before Abraham.
The bible recounts a summary of what happened in greater Sumeria.The Sumerian history is an actual detailed account of a battle between what then were considered “gods” of heaven and earth.
The Adam of the Bible came before the tablets of Sumer were written.
As for the “gods” or demonic hybrids before the Flood... of course they existed... though don’t look to me as one who canonizes the book of Enoch, when God did not see fit to do so Himself.