I have sometimes wondered if ideas about dwarves, gnomes, trolls or other vaguely human-shaped mythical creatures might have originated in encounters with other, now-extinct human species.
Dwarves are short people, so there's really no mystery there. As for gnomes and trolls, they could be explained as birth defects. The myth of "changelings" are probably these birth defects that might not be noticeable in a newly born child, but later become obvious.
I think the real cultural memory of the Neanderthals and other species related to us is in the myths of Titans and Giants. People who were on earth first and who battled furiously with man-like gods for dominance.
No, probably not. The word “Zeus” is far older than Greek - it’s a Proto-Indo-European word, and he is an Indo-European sky god, with analogues from India to Iberia. (“Dios,” as in the Latin languages’ word for the Christian god, has this derivation.)
This all to say that the word (and the sacred culture attendant) is far older and far broader than can be ascribed to some just-so story of a prehistoric, let alone proto-Greek, warlord. If I were to look for origins of “Zeus,” the god, I would instead first contemplate how vast the sky appears when seen from the steppe (whence the Yamnaya, first speakers of this language family). How does one not imagine a sky father in that seeming infinity?
Nothing you wrote here negates what I wrote. Just that it goes far back, and probably originates in pre-history. Its not inconceivable to think about figures like Jesus existing 20-30-40k years ago. Over time they turn into legends, which are bigger and more vast than the living human ever was.
I think the real cultural memory of the Neanderthals and other species related to us is in the myths of Titans and Giants. People who were on earth first and who battled furiously with man-like gods for dominance.