wild theory
Yeah, I mean, why else would some random person casually slide down the clearly evil, dangerous, haunted, anomalous, man-eating slide, to go into the temple and feed.. "them"? They probably only ran at the end because they knew they'd be killed. I'm not sure what other kind of person would release the chains to drop that pulsating lump of flesh in the pit.
"Ride A Slide
Participate In An Ancient Ritual"
Well, I guess they don't have to have prior knowledge of it, but it seems reasonable to me.
Ah, Right. Plus, where'd the struggling person stuck in a bag come from? Maybe the player character was the one who prepared that sacrifice for the ritual, so that they wouldn't be sacrificed on the altar in step 1. Otherwise, it'd be awfully convenient timing.. Though with the space manipulation, it could have been done by the slide on purpose, and the monster was just out hunting and just came back while the player was about to leave the time-skipping slide.
Whatever the case, the Player Character has zero characterization, besides conveniently doing this whole trip with seemingly no preparation or buildup leaving unscathed, and refusing to leave the area before he's done with the ritual. He could just be insanely curious, but.. Well, that or the fact that the player can't leave because of invisible walls isn't part of the story.