You don’t have to subscribe to all of them, just subscribe to the ones that give you the vibe you like.
There’s no such thing as “official” communities, because every instance could potentially be the next big thing, and every instance could potentially disappear tomorrow. That’s sort of annoying for people who just want one good community, but it’s one of the strengths of the fediverse. Some people will really like one instance and some people will hate it. Unlike with reddit where there’s only one /r/books, there’s as many as we have instances and people can go where they like and avoid where they hate.