Indeed, and even more on an aggregate basis, the population also being much smaller.

> modern capitalism hadn’t had time to create

You're assuming that was created by modern capitalism, which I think is a major flaw. Capitalism contributed certainly, but so did democracy, freedom, rule of law, government investment, civil society, etc. etc. Just look at most of the education system, courts, security, roads, most of science, soldiers, etc etc etc.

> abundant, filled-with-medical-marvels lifestyle we enjoy today.

A great many, maybe most people in the US don't live in that world.