You would be correct in your presumptions. Before our current era, magic was completely nonexistent for humans. Nowadays however, it's being discovered that many humans have a sensitivity to magic. That being said though, magic in the Commonwealth is very much in it's infancy. Humans are still learning the rules and learning the basic fundamentals of magic. Those who are able to use it are amateurs at best. At best, they're able to start a small fire. At worst, they're simply able to detect other magic users and don't even realize it. In regards to war mages, yes. The Commonwealth has begun enlisting the aid of thae mages in aspects all across the army itself. Storm mages who can conjure brutal lightning storms in the Artillery division, healers within the infantry, the Thal have even developed a form if sympathetic magic to repair vehicles and push them past their normal limits.

As far as the Iron Crown is concerned, no one is certain of their magic use. Since they landed on Thaejhal, they have been gunning down its inhabitants indiscriminately. Sort of hard to learn magic when you're shooting down the people who can teach you. As far as the Commonwealth knows however, the Iron Crown employs zero mages and they would rather it stayed that way given how they abuse science and technology

[@Hawthorne]