Oh, I know that you can't customise NPC genders, but the world generation will usually draw from the male/female/nonbinary selections and the player character's sexuality, there, so I'm basing that particular comment on a slight assumption. And most of these characters will be met via normal gameplay, but it's better to have a list of all the characters and not need half of 'em, than to want to find characters you might be missing but only have an incomplete list to go off of.
It's still an incomplete list, so there's probably still characters missing, and I'm mostly just making it for the heck of it, so slightly incorrect stuff is fine by me lol. When I say 'meet' I usually mean 'they have a storyline they are mainly associated with', as usually you can find several of the student characters just out and about during the day (that's how I found out about the Well-Meaning Athlete, for example). The QB Organiser is also on the cheer team for me, but since she has a storyline there, and that's the title she has, then that's how you would technically 'meet' her.