I would define it as not a mammalian humanoid. So Thi-Kreen, Centaurs, Dragonborn, plasmoids, warforged, lizard folk, etc
I associate "long lifespan" with elves. They definitely aint ethereal, and as for supporters, that depends on the age and culture of your players,
Pillar of what exactly?
ASIs are no longer part of the game. They are mostly for people who see dragon in the title and so want to play one. But they also fill the "not a mammalian humanoid" slot and are a little cooler than lizardfolk. But like elves and dwarves I wouldn’t consider them a “must have”.