Our genus has been using tools, or at least one particular kind of tool, for at least 2.6 million years. Check these out https://en.wikipedia.org/wiki/Hand_axe
Yes, when I thought about it, early humans must’ve been using tools for much longer. I think what impressed me here were the details they were able to deduce: storing tools in a common place, how they probably used them, perhaps the pre-historic equivalent of a butcher shop.
Also, it’s not as if exactly 100,000 years ago, humans turned modern. It was a long drawn-out transition, and perhaps some qualities came much earlier. Which makes me wonder what archaeologists consider as modern and how they arrived at that date. I’ll have to look for the Sapiens book recommended in the other comments.
And thanks for that link, it’s really interesting. I particularly like the linked pages for John Frere and thunderstones, about how stone axes were found and considered in modern times. I find such historiography fascinating: the stone axes were thought to be from gods or fairies at first, then some early scientists started to make more rational guesses about their origin—another approach to deep time.
What boggles my mind is that this particular stone tool, it's so attached to our genus that you could argue that it's a central part of our heritage. For almost two million years this particular tool was made, in similar ways. In some ways it defines us as a species.
And yet we lost the knowledge only 10-20,000 years ago. I find that kind of sad. I wouldn't mind learning how to make one.
When I went to the Maker Faire 5+ years ago, there was one small group of exhibits about making flint tools and other Stone Age implements (fiber cord, then you can make a bow drill and make beads, etc.). They were really trying to revive the ideas and methods hat you are talking about. I don’t have any contact info, but it should be on google somewhere.
Somewhat related for the Bronze Age is the Clickspeing YouTube channel where the guy create bronze-working tools by hand and then uses them to re-create the Antikythera Mechanism. It is surprisingly complex, but he is meticulous and perfectionist with incredible results. Unfortunatel, he stopped posting halfway through, so I’m not sure what happened.
My wife is an anthropology grad, in one of her classes they spent some time learning flint tool making. But it's really a skill that takes years. And of course we don't know for sure how a hand axe would have been made.