But, the physical Human body is always "Human" regardless of the "Controller" of the Body. The stories about Reptilian shapeshifters are based on misconceptions and people who do not understand what is really going on. There are no such things as "shapeshifters" in the physical sense of the word. ALL non-human entities that impose as "Humans" do so spiritually, meaning that they have a Human Body just like you and anyone else. The only difference is the inner self, the spirit inhabitating the body.
The reason there exist stories about "Shapeshifters" is simply because certain people have a more active spirit-vision or "astral sight", meaning they are "psychic" and can see the true form of such beings - and not knowing that what they really see is spiritual in nature, they misinterpret their experience as seeing a Human transform into a Reptilian, when in reality they saw the Human body, and the Reptilian inside it.