Such confidence ratings over unavailable/lost/missing data appear like a luxury to where I'm from (science wise). Does historical analysis come with heuristic privileges over other fields in that regard?
There was certainly a time when discrete knowledge didn't collectively aggregate over generations.
But even in prehistoric times there were things like boat making, midwifery, metallurgy, sea navigating, animal husbandry, farming and seed cultivation, tool and weapon making, navigational shortcuts, the wide variety of spoken languages, medicinal knowledge, knowledge of fresh water sources and hunting techniques ...
Squaring the number to 40,000 years isn't far back enough. 200,000 years ago, for instance, people weaved grass beddings out of on insect repellant plants, wore clothes, had shoes ... Seafaring is at least 130,000 years ago.
Specialization and collaboration is a core part of being human.