Initially, I considered some additional endings, but I didn't have enough time to implement them and the jam was about to end (the submission period). I even considered giving David and Iris a somewhat "happy ending" where they lived as a couple and David kept murdering people in secret, but ultimately discarded it. Perhaps in the future I could add at least that ending as an additional bonus.
The other undead entity is supposed to be another ghoul (i. e. a really evil person who eventually became a ghoul some time after their death), probably someone who belonged to the cult and was left forgotten in that area. There were supposed to be even more undead entities, but I was running out of time.
Maybe one day I'll continue the story.
By the way, the canon ending is the third one, where Iris stabs David. David isn't dead though; that's why his body was never found (the entity inside him was actually awakened by Iris' attack)
Thanks for playing!