Yeah, I’m keen to agree with you, since for me it’s the complete opposite: My armpit hair seems to trap humidity against the skin even when air can get in there, and the smell of the sweat sticks to the hairs so if I sweat even momentarily a few times it’ll start to smell whereas it evaporates better if I keep it shaved.
I use an electric razor so it’s more like a really close trim than a clean shave though, practically never have problems with ingrown hairs, so that’s something I’d recommend.
I think innovation is easier when you’re not constantly preoccupied with survival, having to spend every waking moment worrying about starvation or predators or disease or freezing to death probably puts quite a bit hamper on what creative new ideas you are able to come up with and try.