They're task-performing entities. There is no single ENA as everyone has already figured out. They are a simulacrum, a vague recollection of some existing individual assigned to some specific role. They are made by (and drawn to) promises of salvation. This is how the original person becomes ENA to begin with. The task reflects the original person.

This ENA seeks out the boss (who we have already seen in merch, he is the clown guy) because he is very overtly a devil and an orchestrator of misery. This ENA a saleswoman. She is quite literally trying to sell him on the idea of allowing himself to become ENA because that is what she did, believing she could escape her atrocious past. This ENA is a saleswoman because her past involves being a partisan "true believer" violent monster.