That's like saying coastal sea level rise is nothing to worry about in places like Florida because that whole area was at the bottom of an ocean 100 million years ago.

Hint: https://xkcd.com/1732/

Did you mean “humans or capitalism”?

In any event, who cares what the climate was like before humans walked the planet? We do care about what it is like while we’re around because it puts significant constraints on our lives.

Earth has, human civilization as we know it has not.