In ancient Mesopotamian mythology, Humbaba was an evil giant slain by the hero Gilgamesh in the famous Epic of Gilgamesh. In the epic, there was only one Humbaba, but for the purposes of this question let's imagine there's a viable population like any other species.
Accounts of his appearance differ depending on the translation of the poem, but I'm going to with the one described in George Burckhart's one.
(Picture potentially NSFW)
In it, Humbaba is described as having:
- A face like coiled intestines
- Paws for hands
- Thorny scales
- tail and phallus ending in a snake's head
- horns like a bull's
- clawed feet
Just like any giant, he is much taller than a standard man and has an overall humanoid body plan.
How could this organism plausibly evolve said features, and what would it descend from?
I don't mind if some of the more minor features are omitted, such as the paws, which are hard to justify in a bipedal animal.