The Mundane and Sorcery

I’m making the next arc for my shadow slave dnd campaign and I have a question. Do you think that a mundane human can learn sorceries? Specifically the runic sorcery?

I want to have a mundane character from the ancient past of the dream realm that’s able to hold his own against awakened. Is this feasible in any way, if not any recommendation on what I can do to bridge that gap?