But is P5 really trying to champion marginalized characters? I always thought it was the opposite: demonizing sinful adults, and convincing those that conform that those in power aren't always in the right. Every character's arc starts out with being a victim of direct abuse from a powerful person. None of them are minorities or come necessarily from low social standing and they are all heterosexuals. They are victims first.
Ann is a particular example here. Marginalized? Hardly. There were rumors about her and Kamoshida, which turned out to be somewhat true, but guys stayed away from her more out of deference to Kamoshida rather than thinking she was some bad person. Girls just exhibited typical high school jealousy. Despite that, she still had a budding modeling career and friends in school. She's no underdog.
Yusuke was a promising art student who was "schooled" by Madarame specifically because of his extreme talent. Haru was the heir apparent to a food empire. Futaba is a literal victim of brainwashing. Ryuji was a track star before he rebelled and may well be the only case of real marginalization. His case, however, was the first real attempt at non-conformity along with MC's arc. Makoto was the freaking student council president and on the way to gathering a lengthy list of college recommendations. Mishima was basically Ryuji without the balls to do anything about it.