Humans never needed to be hyper-adaptive. 80+% of people in the far past were farmers their whole life, just like their parents, and their children, and everyone they associated with. Prior to farming, dumber means of food gathering. You worked your ass off or died but it was never about the latest thing, that's a purely modern invention. Hardly anybody went to "school" or learned a trade, nobody expected job changes every 5 years. You were a dirt poor, uneducated, worn down farmer. The modern invention was the idea we'd have time to be something else (or be a significantly more educated farmer not so concerned with imminent death) and the very recent invention is that you'd need to be multiple something elses over time.

this is absolutely not true. Human history is not the story of hyper adaptive silicon valley disruptors, in fact your completely backwards. Most of human history growth was enormously slow, and only in the past few decades has it really skyrocketed to the point where people become obsolete this quickly. If you were born in 1008 you could be a blacksmith for the next 600 years at least without too much issue.