This is the work of a young Manly Wade Wellman, before he wrote his Silver John stories. Here, the hero is Hok, one of the first modern humans. Yes, he is a caveman, wearing furs and carrying a sharp stick at the beginning of his saga, but over time Hok becomes "humanity's first hero" driving out Neanderthals, learning archery, metalwork, and forging peace between tribes.
This is, actually, pretty good stuff, and containing hints at a broader mythos that explains Atlantis, an advanced civilisation swept away by the (meditterranean) sea. Hok is surprisingly engaging for a guy who wears animals pelts and initially thinks the way to a woman's heart is to steal her away from her family and friends, and Wellman hints that many of the labours of Hercules are much-garbled retellings of Hok's early exploits.
There is also a 50-page short story which is not of Hok, but of his tribe (presumably in post-Hok days) meeting a Martian exploratory force come to take over the Earth, and driving them off: shades of The High Crusade here, and its interesting to speculate if the story was inspiration for that, on some level.
A short introduction by David Drake is also included, telling us that Wellman in fact lived in tribal Africa until he was 7, so he probably had a good understanding of "primitive" tribal man, and lets us know a little about the man. This is interesting and welcome.
All in all, this is not as good as Silver John, but still a solid read.