re: Our ancestors were douchebags,so why do we admire them?

They were. And like all of us, who were douchebags until we learned from the experience of our errs, humanity itself learned over successive generations from that as well.

100 years from now we'll look like douchebags, and 200 years from now the people who thought we were douchebags 100 years ago will look like douchebags. So on and so forth. Humanity is an ever-perpetuating mass of self-improvement, just appreciate your spot on the ride and do your best to keep it going.