Remember that RPGs leave most of the world implicit. When you enter a village with only three houses and just seven or eight people, it's not really that small. The Kingdom of Zeal seems to be very large, certainly with a population at least in the hundreds of thousands and perhaps many more, with more than just the few cities shown on the map.
This means that, just as in the real world, no one character such as a Guru or the Queen of Zeal would be able to teach magic to everyone. Because it seems that the only difference between Enlightened and Earthbound ones is the ability to use magic, and this is without any concrete exception, we can imagine that everyone in Zeal is born with the ability to use magic. These skills would no doubt be disciplined in children by their parents and teachers. Perhaps high-level students study under some of the Big Names, but ordinary Zealish wouldn't have access to the valuable time of those types.