Capitalism is a tool intended to fix these very problems!

What definition of capitalism are you using here? Because I think most commonly-accepted definitions definitely do not assign this as an intention of capitalism.

Strong regulations, moral actors, and careful control can fix many of capitalism's problems. But the kind of unfettered capitalism that, for example, anarcho-libertarians espouse would certainly not lead to less environmental devastation, oppression/wage-slavery, and/or mis-allocation of resources.

Historically I think most people would agree capitalism is in a better state than it has ever been. Capitalism as practiced in the late 19th/early 20th century was very different from our understanding of it today and was much much worse across most dimensions. That is a result of evolving regulatory frameworks making capitalism more compatible with what we define as happiness, justice, and morality. Hopefully we can continue curbing the issues of capitalism while encouraging the things it is good at (like making numbers goes up and creating lots of shiny things people like).

It was worse to be a farmer owned by your local feudal lord, no?

Definitely true. But this is not a problem for most capitalist critiques; that the current system is better in some ways than others doesn't mean it also isn't bad.