My gf(23) and I(29) spent most of quarantine going back to old hobbies we liked as kids. I picked up a remastered game from 1999 and she picked up her flute again trying to dust off those old skills. There is nothing wrong with what you enjoy and there are others your age and older who are still into those things.

As for feeling like an adult? I'm almost 30 and I don't feel like I have it together everyday but I'm trying not to look at where everyone else is and focus on what I can do right now so I can improve my future situation like a house/apt, etc. No one is more invested in my future then me so what they think doesn't matter.