Our distant ancestors were hunter gatherers who relied heavily on their wild instinct in search for food, they also had a basic concept of social status with the alpha male leading the clan.
To perform magic certain regions in the brain such the occipital, frontoparietal, posterior parietal, precuneus, and dorsolateral prefrontal regions of the brain would be more active. These portion of the brain governs our imagination, I'm not doubting our ancestors ability to think abstractly... I know these hunters are very cunning hence exhibits creativity but they simply predict the movement of their prey. Borrowing experiences from earlier kills and applying the same kind of logic that lead the prey to die from exhaustion and cumulative blood loss.
Okay I admit these people probably don't think in abstract so how do they manipulate magic? or is there any kind of magic that doesn't require imagination? I'm probably writing a novel or game regarding magic in the prehistoric world and the magic shares similar traits with DnD.
Comment below should you have doubt, don't hesitate to remedy my English!