I think we could always find a thing that made the next big innovations possible. Newton said that we are standing on the shoulders of giants. I also wondered the other day if humanity could rebuild the current level of technology given a select team of our brightest and all available knowledge, but no tools or machines. We would have to recreate so much in lock step to event get to the most basic things. Just think of how much effort and technology is required to manufacture a simple ball pen.