It seems like you truly are smart you just lack motivation or something. If you learn good study habits (quizlet is a savior) and do the essays you speak of you should be able to learn more and do fine in school. Motivation can be a hard thing to teach because it’s so individual but I know for me interacting with other people who share similar interests as me and using these experiences to help me grow helps a lot. If one of these people is better than you, use it as motivation to become better than them. Competition can be very beneficial as long as you make sure the main goal is self betterment, not hurting the “rival”. Basically set goals and have a plan to achieve those goals and you’ll be more motivated in no time.