WOW! No Human could possibly have a weirdy beardy like that! That MUST constitute Gilgamesh proof!
Oh, wait. Humans look like that all the fucking time. It looks like we'll have to wait a bit longer for proof of Gilgamesh.
Of course, proof of Gilgamesh should have been laying around like leaves in autumn for millennia. Since we have ZERO examples, the only rational conclusion is that there's no Gilgamesh in the fucking FIRST PLACE. End. Of. Story.