However, it’s impossible for him to do that and the creature catches up to him. This is probably the realization that causes him to shoot himself afterward bc he knows he can’t escape what he’s done and it's the only way he can escape responsibility.
Because the creature is an amalgamation of the company's mascot I think the creature is also meant to represent how he was the one to crash the ship and get them into this situation. So by him running away from it, he’s trying to avoid all responsibility.
Showing how he can’t take responsibility for what he did to Anya. However, at the end of the level no matter what you do the baby/creature catches up to him showing how he can’t run away from this.
When you use the ultrasound machine it shows the horse skeleton which could be referencing what jimmy wrote about on his mental evaluation to Anya. The baby is supposed to be jimmy's and Anya's, which is clear from the baby sounds and how to complete the level jimmy has to try and run away from it.
I was trying to watch video essays on mouthwashing and found no one was really talking about the ultrasound scene so here’s my best take on what it could be 🧵
