[@Xistina] my original thought was to forbid magic altogether, but your idea has actually made me reconsider.

My main concern with magic is that I'd like to encourage average characters: shepherds, woodcutters, foragers, even children. I don't want anyone to feel they have to create characters that have abilities to compete with master magicians.

However, you raise a good point in that magic can be ingrained in the tribe's culture. So to answer your question, everyone is free to create a magic system for their tribe, but it's certainly not necessary. How magic is perceived depends on the culture, since every tribe may have different experiences with it.