Genesis is Old Testament, not Christian.
I always get a kick out of the fundie claim that God changed humans at some point: after Eve’s “sin” God changed her anatomy so that childbirth would be painful and difficult; at some point after Adam and Eve, God changed humans so that incest became a genetic problem; after Noah, God changed humans so they could eat meat.
Evidently God’s creation of man in His image, after His likeness, needed a few upgrades in the early days.