First please don’t ban me I’m new.

That would be a silly reason to ban you for dont worry your good. ^^

lemmy.world, lemmy.ml , lemmy.xxx, lemmy.whatever, etct… + hundreds of clones. Is each of these a Reddit by itself containing many subreddits inside it?

Sort of but it is all connected so if you view all you will be able to see all the lemmy.insertname that are connected kind of like /r/all but it includes other lemmy sites. (Think of it like crossplay between playstation and Xbox if that helps.)

Does that mean if someone in lemmy.xxx/c/jokes posted something interesting that I wont even see it because I’m signed up in lemmy.yyy/c/jokes ? It will still appear in (all) regardless but you can also search in (local) if you want that specific version of /c/jokes

That is quite a weakness of lemmy compared to reddit. Can I post on lemmy.yyy if I signed up for lemmy.xxx or do I have to sign up for each of them? No you can view and comment on other instances

Which one should I sign up for? Any is fine though Personally I chose Lemmy world and kbin social.

How can I see all lemmy posts in one place? I can’t believe no one has found a solution to this yet and just let hundreds of clones post repeated things. Also how is each moderated? Is lemmy.yyy moderated by sensitive snowflakes who ban anyone who cusses or offends anyone, while lemmy.xxx is ran by racist nazis? How does this work? Instances can block other instances aka defederating think of it as one country putting an embargo on another. For example we have defederated from a maga instance and a tankie instance.