Humans: No magic, may have Sight

Mages: Have Sight and some magic, can bond with a Familiar to use proper magic

Fae: Are magic, can only be seen by those with Sight and can become a Familiar (include every sort of mythical creature, as long as they are sentient). They can use some simple and weak magic on their own, but need a mage to use proper magic

Arch Fae: Fae who are magic and don't need a mage to use magic

Guardian: Beings who are super powerfu and who guard and protect the balance of magic

Extra explanation cause why not: Humans are empty flashlights shells. Those with Sight can open the flashlight and see how it all works. Mages are flashlights with the metal bits the make the battery work, and they might be able to use tiny batteries with a few seconds of power. Fae are endless batteries, and they can produce energy but don't have a flashlight to turn it into light. A bonded pair then is a mage and a fae, a flashlight with all the parts and a battery to run it and make light. Arch Fae are the weird shake-able flashlights that power themselves, and guardians are supercharged massive spotlights. (Idk how much sense this actually makes, but it helped my friend understand it so oh well)

All Living creatures have a primary element. There are 4 elements (Air, Earth, Fire, and Water) and all the elements can be influenced by Dark or Light (ex. Earth + Light makes Plant magic, and Earth + Dark makes poison magic). Mages can use all 4 elements to some degree, but Fae can only use the one they belong to. When a Fae bonds with a mage and becomes their Familiar, the mage's magic shifts to match and the mage will struggle to use any other magic. In turn, they will become much stronger in that magic, drawing power from the Fae.

Familiars are made when a Fae matches with a mage and their magic and personality. Every Fae has different standards for who they consider worthy (for example, some would prefer dumb courage over intelligence or some would prefer kindness over magical ability). Fae that become a familiar and are permanently bonded to their mage, the only way to undo a familiar bond is for one party to die, though it usually has disastrous consequences on the survivor

Magic can also be used or enhanced through a conduit such as a staff, wand, or charms, Some mages use one (such a staff), others can use multiples or different types of an object (such as cards or charms). 

Magic takes up the user's energy (kinda like mana), and mages can train to increase their endurance and power. Magic can also affect the mage using it, for example a fire mage is more resistant to heat, but is not necessarily fire or heat proof and can overheat or get burned by using their magic too dangerously. The reverse is also true, so a mage that is more resistant to one thing becomes weak to another (in this case, the fire mage would be weaker to cold). All of this also applies to Fae as well, though to a much greater degree. A fire Fae would be immune to fire and heat, but very weak to cold or even water.

Example Character: Isra is an Air mage, Her familiar is an Fae named Eteri. Eteri has Air magic with a Dark alignment, making his magic, and consequently Isra's magic, into Dream magic (air element is closest to mind, light influence would be something like divination). Isra specializes now in Dream magic, and uses folded paper charms as her conduit to create more powerful illusions or dreams. As a Dream mage, she has much more vivid dreams herself, and overuse of her magic can cause insomnia and mental instability.