Neanderthal Challenge

The Neanderthal was not a human ancestor. Even organizations like PLOSBiology agree to that (DNA described as roughly halfway between ours and that of a chimpanzee. The more recent claim of humans and Neanderthals being "cousins" with a common ancestor (Heidelbergensis) four or five hundred thousand years back is idiotic; too genetically remote to be ancestral to is a transitive relationship...

The Neanderthal was a very advanced bipedal ape with huge dark-world eyes, a typical ice-age fur coat (no Neanderthal needles), no forehead, and a brain which, while larger than ours,, was dominated by the area of the brain involved with vision. That combined with the huge eyes means that the Neanderthal in his heyday on Earth never saw anything we would call daylight, just the purple and ultraviolet light you would associate with a dwarf star such as Saturn was 150000 years ago.

More recently, he encountered two things that, ultimately, he was not able to deal with, i.e. humans with atlatls and other projectile weapons, and daylight.

The demise of Neanderthals and other hominids:

The Ganymede Hypothesis:
https://steemit.com/science/@gungasnake/ganymede-hypothesis-update