Stark, who had once become the Iron God, understood that the radiance in the little girl's hands could be called magic, or divine power, or perhaps its true nature was the universe's primordial energy.
What the mages of Kamar-Taj called magic was actually the power of the Cosmic Demons, and the power of the Cosmic Demons was the primordial energy of the universe they could wield.
The divine power possessed by the gods of Asgard was also another application of the universe's primordial energy. The reason this race was so superior was that they were born able to use the universe's most fundamental energy.
The energy sources humans could use were also merely the most superficial manifestations of primordial energy, and humans had to rely on tools as well.
Whether one could use primordial energy depended not on the body. The body only determined how much energy could be stored, like the Ancient One when she looted a drop: the stronger her body was, the more energy she could store.
The key to using primordial energy lay in the soul. Only a soul with special properties could touch the most fundamental energy.
A soul born from the nascent power of the universe's first bolt of lightning, like every Asgardian, could naturally access primordial energy. Or rather, she was actually a descendant of the gods.
Although she looked very much like Loki, that might have been because the first thing she saw upon hatching was Loki in midair. But in principle, she should have been an Asgardian, because what ignited the fire of her soul was Thor's divine power, and Thor was a pure-blooded Asgardian.
After hearing Schiller's explanation, Stark's eyes widened as he looked at the little girl. "So she's an Asgardian, and she can use an Arc Reactor too?"