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.
Some of the prehistoric novels contained elements such as the Cangli Clan, the Yue Jian Clan, and the Nine-Headed Clan. However, the search results didn't provide any clear information on which novels contained these elements, as well as their plots and story content. Therefore, he could not answer this question accurately.
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.