The idea that "why did the world not figure out governments can just print more money at negative interest rates in the first hundred thousand years of civilization?" is an interesting one. But the key I think misunderstanding here is that the world only "invented" a truly fiat-based currency with no physical base like gold in the 1970s when Nixon broke from the gold standard. So it is actually a new phenomenon - would not have been possible to do this while tied to limited physical assets like gold... Now the dials can be turned arbitrarily and not have money supply tied to finding a new gold mine randomly.