Actually quite a lot. They were painting and decorating themselves. They discovered complex hunting traps. They painted wonderful stuff on cave walls and discovered much of the world. They had rather complete tool kits made of stone and bone. They successfully lived through some horrendous ice ages. Don’t forget the Toba eruption. All in all, they were pretty busy.
Thanks for your thoughts. MY statement was more rhetorical than anything else. Only God really KNOWS what they were doing; we simply flounder around and hope for the best.