I understand where you are going. If we lost it all tomorrow, it would be quite hard to reproduce tools, machinery, high precision equipment, etc. to get back to where we are. For new inventions, you need both to do all the building of the machinery that builds that machine that will build the new invention, but you also need the novel new idea that is the invention to be made. 2 hard (and quite different) problems to solve, instead of just the first (which, as mentioned, is ridiculously hard in and of itself).