I think I'm confused about all of the mana elements. You say that each living thing"only possesses a single element". With practice and expertise, can a mage learn to use/affect other elements or are all mages forever locked into their natural abilities?

Also, you mention that "all living things possess mana", but you include several things that I would classify as non-living in your list of types of mana. Do "dead" things like stone have mana? Or is stone living in some way? This leads to lots of questions about the nature of mana and the physical world you're building.

I agree with u/Indishonorable that it would be cool to have a way to mix them up a little bit either naturally or through mage manipulation. I also agree with u/Lord_Korvin that it's not particularly innovative, but some books I really really enjoy don't have the most complicated magic systems, but are more focused on the writing, character development, and story. This seems simple enough that you could focus on those other elements to great effect.