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.
The phrase " A man can be destroyed, but not defeated " came from the novel " The Old Man and the Sea " by the American writer, Ernest Hemmingway. This sentence tells us that when a person faces setbacks and difficulties, the most important thing is to maintain a strong heart and a positive attitude. No matter when, difficulties and setbacks were the norm in life. If a person did not have enough inner strength, it was easy to be defeated. However, this sentence also conveyed a positive message. Although a person might experience failure and pain, their spirit would never be completely destroyed. This kind of tenacity and unyielding spirit was the key to overcoming difficulties. No matter how big the setback, a person should maintain confidence and courage, and persist in pursuing their goals and dreams. This sentence inspired people to face the challenges in life and persevere in pursuing their ideals.
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.