Ever notice that through litterature, movies, paintings etc... That any form of monster or alien is represented as a mutation of a human being? They usually have two arms, eyes, nose, mouth, head, shoulders etc... Monsters or Aliens are just humans with some sort of change to their physique. It seems that the human mind and imagination can't think of a creature that doesn't resemble a human in some form.
Proof. Just think of a monster or alien in your head. It will have a resemblance to a human. our minds can't think of a creature that doesn't resemble something we already know.
I need to smoke less weed....