I've sometimes wondered about this as well. We can all understand how saws work; but can you actually make one from scratch? How about a rope? Do you know where to find the right kind of fibre, how to correctly process it, and then make it in to a functional rope? Do you have the know-how to functionally domesticate wild animals and cultivate crops?

I'd consider myself a pretty handy guy, but if I were whisked away to 70k years ago this very minute then I'd probably struggle with a lot of that, even though I roughly know how to do it. And that is ignore the obvious communication barriers, that you also need to spend time on basic survival, and things like that. A lot of these crafts developed over generations partly because while the concepts aren't all that complex, the actual doing of it in a way that's effective is a lot harder.

I certainly think it'll take a lot more than "days or weeks".