I'm not sure about this: lots of humans can make small incremental progress. For every Isaac Newton or Terry Tao there's a 10 or 15 people who are a few years behind them.

Carl Friedrich Gauss illustrates this quite well. He kept a lot of his mathematical discoveries to himself. When they went through his private papers after his death it was found that he'd discovered things years or even decades (or centuries) before anyone else published them. It's a matter of speculation how much farther math would have advanced had Gauss bothered to publish all his work.