Something about all the different types of magic…
So common it’s regarded as completely mundane. Most people know a cantrip or two, and even those who dedicate themselves to other pursuits (fighters and rogues, for example) are likely to pick up a few things here and there.
Literally: everyone gets 2 Arcane cantrips at character creation, and taking the odd level of Wizard here and there is so common it doesn’t even need a backstory reason for why.
Very common, and very powerful. It’s seen as a direct channel to forces of nature; very few suspect that this is also a direct channel to The Arch Fey.
Other types of magic
For example, some creatures have their own small magics, though they’re rarely as powerful as the magic of humans and half-breeds.