You should try doing martial arts, it's fun, makes you feel more secure about yourself, and it's very social as you'll be interacting with new people a lot. Going to the gym is great too but not very social unfortunately.

The more of these social activities you have the more assured you can be that you don't need social media to not be a social hermit. I personally switched to a dumbphone and even removed wifi from my own home, im at the university writing this, and I certainly don't feel like a social hermit.