What books should i read before I'm 20?

I'm 18 and looking to understand people and the world better. As an introvert, I've always struggled with confidence and courage, but books have been my safe haven. I'm seeking recommendations for books that can help me understand others and myself better.

P.S I'm not looking for self-help books 😅. For some reason, I never remember them. Non-fiction is great, just not self-help. Any impactful book that sticks with you would be perfect. Thank you!