There is no sentience in the 5 pure Elemental Planes–that we know of–although you gotta wonder about the plane of Spirit. Remember it’s the interaction of these planes that creates mana, animus etc. So a “pure” plane isn’t going to generate life or magic on its own.
The demi-elemental planes seem to be different. There are sentient beings that live there. I think they are ‘native’ but not really sure. But certainly since they are transition zones, they have elemental mixing which could create life and magic.