“American Beauty” is a comedy because we laugh at the absurdity of the hero’s problems. And a tragedy because we can identify with his failure–not the specific details, but the general outline.
The movie is about a man who fears growing older, losing the hope of true love and not being respected by those who know him best. If you never experience those feelings, take out a classified ad. People want to take lessons from you.
Roger Ebert
https://www.rogerebert.com/reviews/american-beauty-1999