What makes a good protagonist?

Seems to me like you're creating a rebellious-type character, if I'm mistaken? I am fourteen, just starting high school, and am writing a fantasy/greek mythology story myself. I plan to use the next three years writing so I can publish it at 17 or maybe 18. If not the latest, then 19. I've been writing for eight years, and perfected myself to an intermediate status. I can say much, since I don't know much myself. All I can say is that to perfect your character more, trying to looking at books on character traits. I've been looking myself. Also, try to give reasons as to why your character is the way he is, but not too much. Look at J.K. Rowling, when she made Harry Potter, we didn't know much at him until the end. Well, if your story is in a saga, try to head for that approach. Maybe your character's parents died or his parents neglected him, making him distrustful of people because he doesn't want them to do the things his parents did. Maybe he's paranoid because he's been traumatized. Maybe he's hellbent because someone did something terrible to him. Maybe he has only one friend since many don't like him, and if he loses his best friend, then he'll have no one. Stuff like that. Hope you do well.