Usually the mana that existed on a world would affect the inhabitants based on their environment, giving them advantages over whatever the overarching theme of their world was.
Desert worlds had an abundance of water mages, inhabitants of water worlds mostly specialized in wind magic, and those who lived on barren worlds commonly had increased vitality and physical abilities such as endurance and enhanced senses to ensure they could survive. These were just to name a few, but just because a world specialized in a certain type of magic didn’t mean everyone was affected by the mana in the same way.