I think your view is tainted Already, Elements aren't Colours.
*yawn*
But that's the problem - humans are not elements.
humans are tool-wielders, not tools themselves.
they would be users (abusers as well) of Elemental sources, as they themselves ARE all the elements combined, in a manner of speaking.
I think adding humans would be a big mistake. There are Mages, Clerics, Fighters, Bards and Elves in every single fantasy game out there. Why on earth should Elements follow the same path?
nobody suggests we make the dullest possible combination between Elements and human.
like the card Immortal. it is as human as it gets, really, as what elemental creature
wears a cloak, heavy plate armor and has two bright eyes? I think I even see a sword on his back.
in a loose, creative way, we could say it was a human that has achieved a high-enough level of Aether mastery
that he himself was emerged.
this is very loose, but I do feel it should be like it.
many creative classes and definitions can be like this. Mummy, Pharaoh, Fallen Elf, Skeletons, Graviton Mercs and firemasters... ain't we already emerged in humans?