"Innovation" really started accelerating when we started using agriculture and had division of labor. An aristocracy (not sure what's the best term here) would form where some people had a lot of free time, and didn't need to spend all their time hunting/gathering/building/migrating. This enabled them to follow intellectual pursuits. All of this was at the expense of everyone else though. It's still kind of like that with wealthy nations extracting wealth/labor from poor nations, allowing the wealthy nations to spend some money funding universities and research.