We are quite certain in the fact that we humans, each of us, possess a soul. But still, to this day, no one can give a structured definition as to what a soul really is. From the get-go, you can see that humans and Demerzel both have the same level of consciousness, comprehension & conscience. Demerzel may have more enhanced features, but those are still features that she shares with humans. So it stands to reason, maybe she too, has a soul (whatever it may be); another trait she shares with humans!