@Gentlemanvaultboy If that's what you want to do, go for it. The only way it could be disruptive (In my opinion) is if somebody decides that they would like a Caveman/woman character since the cave-people and Reptites hate each other.
EDIT: If you find that that would be disruptive, Robots are available as well as transformed humans (Like frog was)
EDIT EDIT: Remember, Robots, Cave-people, and Reptites don't get magic. In order to have magic, one must originate from after antiquity and originally be Human.