The term "non-magical" does not refer to a singular race. Rather, "non-magical" is a classification of race, like "Magical" or "Monster".
Non-Magical races are the races that were trapped in the Living Realm when the world was sundered.
The term "non-magical" is a misnomer; with the exception of Humans, all races contain some magic. Even in the magic-devoid Living Realm there are those of the non-magical races born that can practice limited magic. It's limited to simple spells and small effects, but even the ability to conjure a small flame or a gust of wind is huge compared to nothing.
Most non-magical races have magical traits or abilities. These are often expressed in their signature skill. For elves, for example, it's in the ability to craft mythical weapons, or their ability to drive concensus among opposing parties. For Gnomes, it's their ability to understand mechanical devices, or creat things that probably shouldn't work, yet they do.
All non-magical races (Humans especially) can be corrupted by high concentrations of magic. This corruption can cause them to lose their sense of self, giving into more base desires and passions. A lust of power and control is common. Depravity and a sort of beastial insanity can follow. Exposure to enough magic can even cause physical changes. This corruption is called, by some, "monsterification", since it follows patterns reminiscent of monsters.
(Non-magical races cannot, however, be turned into monsters without the guiding hand of Umumtu herself.)
This corruption is slow, and given enough exposure to Living Force, reversible. Those recovering from magical corruption find natural places like lakes, fields or forrests to be especially healing.
See the History of the Living Realm.
Non-magical races are limited to the Living Realm, and will die quickly in the Magical Realm.