The Phantom Tollbooth
Milo is our main character, there's no question about that. The book starts and ends with him, and he takes us with him on his journey into the Lands Beyond. Despite just being a bored little boy at the beginning, he's good-humored and manages to acquire buddies and knowledge and to be the successful hero of a quest to boot. He doesn't know as much about words as King Azaz, or as much about numbers as the Mathemagician, but he succeeds anyway. Why? Because, like many protagonists, he has a pure heart and willing spirit.