The main character is of course the wimpy kid himself. He's usually a relatable character who has all sorts of insecurities and problems. There might also be his friends, like Rowley. His family members, such as his parents and his older or younger siblings, could also be important characters in the story.
The main plot is centered on the kid's experiences. He might be facing typical problems that kids his age face. It could be about his relationships with his family, friends, and teachers. In the context of the 'cheese story', the cheese could be a symbol of something disgusting or feared in the school environment, and the story could be about how the main character copes with this strange and smelly element in his school life.
Sure is! Diary of a Wimpy Kid is a fictional novel that follows the adventures and daily life of the main character. The books have been loved by many young readers.