I think that JJ2 itself is a Universal game(As in the kind that's suitable for everyone, but still fun to people who aren't Children(Like Sonic, Mario, Rayman, etc.)). Even Online Multiplayer is suitable for kids, just as long as you have a decent "filter.lst" file, and keep them away from those... Unsavoury Servers(Although those don't appear too often).
I think Jazz2Online(I don't mean the JCF or any other Subdomain of J2O, I'm talking about just plain old Jazz2Online) is... Sort of debatable. There are some questionable things here and there, but it's mostly suitable for all.
The JCF, though is definately for Teenagers and older.

So, overall, when boiled down into a few words: I think that JJ2 itself is for everyone, Jazz2Online is debatable, and the JCF is for Teenagers or older.