Looking For Advice and Criticism On my First Major Worldbuilding Project

I apologize in advance for my terrible formatting and disorganization.

https://docs.google.com/document/d/1KxA-XrDSvVrEdCHnvfY-pawhgTvcgcqJHisvIh50YT0/edit?usp=sharing

I'm specifically looking for advice on how to develop cultures and magical systems. I would also be interested in seeing if this kind of world has been done before and how different aspects were implemented.