Aliens can look human, The Doctor is an alien and he looks human. Superman's an alien and he looks human. She looks like she's not what she seems, like this is just a disguise or she's going to shape-shift into something else, I think it's the red eyes that give her away.
"Doctor: No, I don't look human, you look timelord. We came first !"
So , yeah she looks very human, even if her Skin looks abit like plastiv , her eyes are kinda scary red and she uses some kind of light-dagger , yes she has ahuman form. But that doesnt mean she has do be human. Don't judge a book by its cover folks I love this piece of artwork.