Before capitalism, people used to only kill as many animals as were necessary to feed them

Are you serious? Abusing animals for sport and gambling was widespread, across many cultures, millennia before modern capitalism.

The Wikipedia article on bloodsport lists plenty of examples of human on animal or animal on animal violence to the death.

And that’s to say nothing of the use of non-consenting human slaves for blood sport.

There’s something to be said for the cruelty of industrialized slaughter, but let’s not pretend that human cruelty to animals isn’t part of our nature that predates capitalism.