You combined elements in such a way that the whole is larger than the sum of its parts. Well paced, the level design was constantly shifting keeping up the challenge.
Near the end, by introducing to the player the text "overcome fear" you set the expectation that what follows is dangerous which is a clever trick to evoke a specific interpretation of the aesthetics.
The final part managed to merge the identities of the player and the character - what was suspected was uncovered but was that the motivation or was it the journey itself? Introducing a seemingly important choice at the very end is another clever trick - this time used to invite replaying.
One potential game breaking bug - I naively made the character collect all the heavy creatures and he just could not move. There was no way of knowing that would be the consequence. So I quickly thought to press E to drop them but since they dropped on the same spot the next time he returned, the character picked all of them at once getting himself overburdened again. After a few loops the items fell through the ground and luckily fell near whey they needed to be. I think an easy solution to this would be to limit how many of them the character can carry at a time.
Thank you for this experience. Good luck!