A lathe is the only machine that can build itself. But if all you have is rocks? Asking for iron ore doesn’t do much good, how do you smelt it? Of course there were wooden lathes, but again…
Now if a tall guy with straight legs died you could build a bone lathe (free idea for one of you writers) and tan his skin to make some belts to drive it.
This reminds me of that science fiction story when a mechanic goes back in time but laments, “I don’t have the tool to make the tools to make the tools” except worse.