I have rats and guinea pigs, rats are crazier (but pigs are still crazy) but at least you don't have to wait for a pig to be senior before they sit still.
I wouldn't recommend as a first pet. Rats are super smart and need stimulation. I think young kids would do better with a pet that's not dependent on them, like something that can roam free.
Source: had a pet rat as a kid and did not give it a great life, which is a shame.