Ring world - The magic

The tardigrades evolved and changed along with the rings, and along with the life that sprang forth from them. Being microscopic in nature they oftimes end up inside living creatures, in most circumstances this is simply a short detour through a digestion tract for the tiny organisms. In other circumstances they stick around and form a symbiotic bond with their host. It is unknown what causes them to form these bonds with some and not others, and in fact no one is even aware that the bond exists at all. To those who live on the rings it is simply a fact of life that some folk have an innate ability: either faster reflexes, more speed, ability to breath underwater, perfect distance vision, enhanced hearing, etc.
Then are those who can see and manipulate the energy which flows up from the planet. This energy seems to be limitless in both availabilty and variety of application, however it is heavily taxing upon the weilder. Wrestling with the raw energy and converting it into a practical form, requires a great deal of mental and physical exertion. Some people seem to be naturally better at this than others, though any weilder can match this natural ability with training and practice. An overexpediture of energy has been known to kill it's weilder, either through drawing more energy than they could handle, or underestimating the cost to themselves and sapping their own life force.

Every society on the rings has their own myths and legends as to how those with special abilities came to be, some may even have built religions around them. They all have their own way of dealing with these abilities as societies and as individuals.
Manipulating the energy flows from the planet is universally how magic is done. How the different cultures of the world choose to use or perceive that energy is as varied as they are, but the cost is the same.