Mages
A mage is a human born with the ability to use magic. This ability can only be passed down through genetics, meaning that it runs in families. If a person doesn't have any history of having a past relative who was a Mage, it would be impossible for them to become one.
In general, most start to develop their ability around puberty, or the ages of 9 to 13. While some have been known to be late bloomers, this is quite rare.
All Mages are able to learn how to cast basic spells, brew simple potions, and, with some practice, perform easy rituals. However, to become truly proficient, most mages elect to attend to either become an apprentice to another mage or attend a school. After enough practice and time, they can eventually unlock their full potential. However, regardless of their skill or knowledge, if they ever use up all of their mana, they run the risk of dying.
Each Mage is born with a type of magic that they are inherently gifted at. This also typically will run in family lines. So, if a family member is intrinsically gifted at fire magic, it is highly likely the offspring will be as well. However, things can get muddled when there is the history of different Mage abilities in genetics. It is then usually up to chance.
A Mage using their power.
Oracles:
An Oracle is a term for special Mages whose ability specializes in gathering otherworldly knowledge. This can include those with precognition, psychometry, mind reading, or astral projection.
Oracles usually develop their powers when they are young and, as they age, become more proficient. In general, they don't need to be taught how to utilize their skill and will naturally progress with age without the need for schooling or teachings. For them, this power is similar to a sixth sense. These Mages are typically taken as children and raised in temples and churches or work as advisers to the leaders of their country.
An oracle, and an elf.
Elves:
The Elves are a magical race who are born with an innate ability to use magic. Due to their intrinsic ability, they are highly proficient. By the time they have reached the age of a toddler, they are able to cast simple spells. As they grow, it is common for them to learn how to brew potions and perform rituals.
Unlike humans, elves do not specialize in any single category of magic. Instead, they are able to master difficult spells if they have trained properly. However, they are in similar danger of burning out and possibly dying if they go overboard in using their magic.