Toge Inumaki is important too. His special cursed speech ability makes him stand out. Also, the principal of the school, Masamichi Yaga, is likely to be important as he is in a position of authority and has an influence on Gojo and the other students. There could be other characters like the members of different clans that also play roles in the complex web of the story.
Well, in my opinion, Star Wars has the edge in fanfiction for this 'Warhammer 40k vs Star Wars' comparison. The concept of the Force is just so fascinating and offers a lot of room for creative exploration in fan stories. Also, the iconic characters like Luke Skywalker and Darth Vader are well - known and loved, which makes it easier for fans to write engaging stories. Whereas Warhammer 40k can be a bit more complex and intimidating for new writers in the fanfiction world.
It's hard to pinpoint exactly where Gojo is at any given time in the manga. His whereabouts change as the story progresses and different scenarios unfold. It could be in a supernatural realm, a mission site, or interacting with other characters.