OH MY GOD THE UPDATE WAS AMAZING!!!
SPOILER ALERT!!!
I can't believe I didn't think of a rabbit during the times I was trying to figure out who the white thing was. Despite the huge chunk of solved questions, I somehow think that the update was a bit shorter than the rest, since Dave got injected and passed out before night time. A new character would've made sense as the killer, but some might forget this little detail. Jack was the killer but not the main suspect because he is being paid to "do the job", which is kill everyone. Also, it means that there is someone or something paying him to kill them all and only that, because Jack also mentioned that he just came in a week before. Despite everything, I honestly wished Day 12 ( Bad Timeline ) came out today too, but I understand if you didn't have enough time to finish it. Thanks for the great update! (I'm literally listening to "Purposed Stroll" right now)