Seems to me like a lot of the difficulty would be that the natural resources you need, in the absence of civilization, are scattered all over the planet, let alone deep underground.

I vaguely remember reading something about how even in the earliest days of making flint arrowheads, there were massive centralized mines that archaeologists have found. It wasn't like just because you were in the stone age chipping rocks, every location was equally accessible to the resources you needed. Similar to now, where you need a particular type of sand for concrete, or for fracking, or...