At the moment I'd rather not get involved in an online argument about which economic systems are better than than which other ones... especially not on a forum run by a startup accelerator, with a constraint that my preferred system has to be more than 300 years old.

I just wanted to point out that capitalism is in fact a specific economic system. It's not a law of nature, or another word for "markets" or "freedom", or a realization that some other system doesn't work.

Your question assumes the only alternatives involve going back, not forwards. There are still many untried sociopolitical systems.