Never fit in 😔 idk what to do.

I never connect with anyone at school. Nobody talks to me and I have no friends. I try to get to know people but they never want to get to know me. I ask people to hangout but never do. Idk what to do and why people don’t like me. I have done activities outside school but there’s nobody my age. I feel mentally 20 years older than my peers. I don’t know what to do. I like doing things in my own but sometimes it’s isolating. I don’t even know what other people my age do because I’m never included. Any advice please?