IF Adam was not a literal man, then today's people would still be looking for a hole to sleep in tonight. Gen 3:22 ONLY Adam was made with a mind like God's which means that ONLY a literal Adam could have passed his superior intelligence to Noah.
When Noah arrived in the mountains of Ararat, his unborn grandsons, also arrived. Like Cain, on Adam's Earth, they had NO other Humans (descendants of Adam) to marry. Like Cain, they married and produced offspring with the sons of God (prehistoric people) of Adam's Earth
AND on the present Earth, fulfilling the prophecy of
Gen 6:4 of "and also after that". IOW, Only the descendants of Adam have INHERITED his intelligence since Nature does NOT evolve it. Amen?