Rumination and depression evolved to help humans survive. They aren't useless.

Maybe they helped humanity but sure they ain't helping me now. I think of them the same we "evolved" wisdom teeth and appendicitis.

Very untrue. Evolution didnt evolve depression, just as evolution didnt evolve every other disease or defect. These are byproducts of convulated systems.

Great point. Some things evolved (by evolution). Then some complications arose because of the different things evolving to their local maximal fitness.

Inability for the human body to cope with something is not the result of evolution but the lack of evolution. Evolution is still going on.

I really can’t conceive of a way in which depression helps humanity survive. Just because we have a trait doesn’t mean it’s adaptive. More likely, it is a dysfunction of a related emotional state with actual utility (pessimism, paranoia, etc), but it is incorrect to say it helps us survive. It’s just not so maladaptive that it outweighs the benefit of the well functioning adaptation, on a population level.

Andrews PW, Thomson JA Jr. The bright side of being blue: depression as an adaptation for analyzing complex problems. Psychol Rev. 2009 Jul

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2734449/