Or maybe Scorpion is a fully fleshed human now...

Nah, most likely an oversight.

In Mortal Kombat 4 in his third costume Scorpion is unmasked and tears it off for his fatality.

I think we have to accept that when Scorpion's face is concerned for simplicity it will be assumed that he has a real face will muscle and such.

So you say Scorpion isn't just pulling off some skin mask, but actual flesh and all... Ew.

I have been dreaming for a fully human Scorpion ever since the beginning. As iconic as the skull is, I find it childish and boring.

I'd like to see a fully human scorpion as an alt costume, like way before he died ,

Scorpions anatomy has always been kinda sketchy.

Does he have a normal, human body from the neck down only?

Is his mask magical and able to express human emotion? (well mostly just anger)

Is he a full skeleton and covered in a sort of living, bleeding, flesh costume?

I sort of just like to put it all down to Magic, hurts ma brainz less.

I always assumed Scorpion's face was always human, and he turned it into a skull for the sake of the fatalities and alt costumes. It's like a taunt.

Yeah, I think Scorpion isn't "wearing a disguise" like 2D-games-Reptile, he has an actual working human face with skin and muscle and all and it just happens to peel off easily as part of his firebreathing ghost-zombie superpowers.

I mean, he's always been capable of making facial expressions with his eyes, and his mask moves up and down when he talks which means his lips and chin are moving under there. That requires face muscles.

I think it's just for simplicities sake in the design of the game.