I’m also toying with the idea right now that maybe Tiger Lily’s people used to happily co-exist with the merfolk, until PP and his minions took the whole of NL over, which is why the merfolk turned nasty. In a scenario like that, Ariel could have observed and even possibly interacted with the type of good people she’d be fascinated by and want to live amongst.
I don’t hold much hope that we’ll see the indians, they’re a pretty random element to appear in a magical land and not an essencial one to the tale to warrant an explanation, unlike the pirates. Furthermore, this take of Peter Pan seems more likely to demand servitude from them or else than joining them in some good old fun.
I could see, however, Tiger Lily being part of the “rest”.