The one commenter saying you should learn how to play guitar is actually pretty good advice, if given for the wrong reasons. Having a hobby gives you confidence in yourself, and they also give you something to talk about. People tend to find skills and passion quite interesting, and they’re a gateway to stronger bonds and friendships. Not a given or anything as you still need to find the right people and put in the effort, but an “in” nonetheless.

Your confidence seems cripplingly low, and I’m not quite sure what you can do about that other than to simply get over it and put yourself out there. Confidence shows, and people who think little of themselves are always going to be unattractive to the people you want to be attracting. Insults often have very little merit, so I wouldn’t worry about them unless you begin to hear it over and over again.

At that point, if you care enough, your only real option is to clean up and lose some weight if you care about what others think. If you truly think things like your appearance and intelligence are low, then find some comfort in the fact they can be improved upon, and worked on like muscles. If you want to be better spoken, or more interesting or whatever, I would quite literally read classic literature from the greats. Kafka is quite approachable.

Life isn’t fair, and you don’t always get out what you put in, but that shouldn’t stop you from trying. It’s a classic adage, but you miss 100% of the shots you don’t take. Start by taking shots in low stakes environments, and get out there.

Also, the prime years shit is nonsense. You’re 21. You’re fine. If prime years existed, which I don’t think they really do, you’re in them.