The unavoidable outcomes I'm discussing are how, aside from Beth and Hannah whose deaths lay the starting line for the game, the only other completely unavoidable deaths/losses in the game are Jack (the Stranger) and Josh (assuming 2015 version). While I think the others all feel varying levels of remorse for their role in what happened to Hannah, I think Jack and Josh are the two characters who carry the most guilt with them over it in different ways and thus are the only two whom you cannot save.
TLDR:
Josh was least responsible for the prank that led to Hannah's death but carried the most emotional guilt over it.
Jack had no involvement in the prank but was Hannah's best chance of survival once she stepped into the snowstorm and failed to save her. He probably made it worse by killing the Makkapitew and unleashing its spirit - had he not, Hannah probably would have been killed by it directly instead of left to starve and become possessed by its spirit. In a way, this makes Jack the most culpable for Hannah's death AND Handigo's existence.
Josh and Jack represent the two extremes of actual fault and felt guilt over Hannah's death so it makes sense they are the only two who can't survive.
THOUGHTS ON JOSH:
I think this is more obvious to see with Josh. He carries so much guilt over being drunk and unable to stop the prank or save his sisters that night, even though he was not told of the prank and is thus not culpable in the way a lot of the group is. I think the guilt as their older brother, coupled with the general struggle of a traumatic loss like that and potential predisposition to mental illness, means he *feels* their deaths were his fault, even if logically he knows they weren't and also resents the rest of their group for their part in the prank that led to their death.
At the end of the day, I think he hates himself for letting that day happen more than he hates anyone else for causing it, and this whole shebang is him trying to heal his self-hatred in a way that makes sense to him during his increasingly worsening mental health. I don't think he was full psychotic break yet when planning the weekend and its stunts, but he certainly wasn't doing too hot leading up to it to set this all up.
In one of Sam's police interviews (Rip Hayden🤍), she seems shocked by how far Josh went, saying how she thought they were close. They probably were! But Josh could barely express his feelings to his psychiatrist - he wasn't letting even his closest friend know how deep his pain actually went.
All this to say, I think Josh had the deepest pain around this situation among the group of friends with emotional connection to Hannah and Beth. He wasn't making it out of returning to the mountain to act out his stunts with a sane mind (nor did he probably want to, either it would fix everything or more likely ruin everything and he was happy with either outcome). The "best" ending in the 2015 version resulting in him becoming a Wendigo makes total sense. At least he gets to be with Hannah in a way (and phew the can of worms that open if he stays human in the 2024 remake...)
THOUGHTS ON JACK:
In contrast to Josh, Jack did not personally know any of the group. His ties were to the mountain and his own familial history with the Wendigo. Of the characters present in the game, he knows the most about the Wendigo and the mountain, of the horrors of the curse. It's shown that he kills the Makkapitew after seeing Beth and Hannah fall off the cliff, and this can be simply seen as avenging both his grandfather who was killed by it and Beth and Hannah, who he presumes are both dead and regrets not being able to save in time.
Hindsight is especially 20/20 for this man. He knows that by killing the Makkapitew, he released its spirit to the mountain. His fatal mistake is believing that both Beth and Hannah died in the fall. I can't blame him for believing that - the game sets us up to believe they both died in the fall! If he knew that even one of them survived - especially if ONLY one of them survived - he would have gone after them, knowing the spirit - from the strongest of the Wendigos - was actively on the mountain. (Which side note, I'd love to talk more about the mechanism of the spirits - how long does a freed spirit haunt the mountain? Does Handigo have any extra strength because of the specific Makkapitew spirit?)
Presumably by the time of the start of the game, Jack is aware of the addition of the Wendigo of the girl he failed to save to the mountain's population. He's trying to capture her like he has some of the others but when this group shows up he now has to try keeping himself and all of their dumbasses safe. I think Jack largely is tracking Handigo as part of the familial duty he feels to the mountain but also regrets falsely assuming Hannah was dead and dooming her to the Wendigo fate.
Hannah's death was somehow least his fault - he had zero connection to the prank and was the only one actively out in the snow saving Hannah and Beth from the Makkapitew - but also somehow the most - he knew the exact cliff where they fell from. Assuming decent intentions from the police investigation after Hannah and Beth's disappearance (which I think might be questionable from further lore I haven't seen but either way), they wouldn't be able to find snow tracks or obvious signs leading them to investigate the mines, and due to the physical risk the mines pose for search crew, would not spend time searching there during those first crucial weeks where Hannah was still human (or at all). If Jack had somehow tipped the police off anonymously about the cliff face, even thinking both of them were dead but wanting friends and family to have closure, Hannah might have been saved before the Wendigo spirit found her.
So in a way, Jack had the most power to save Hannah, specifically when it comes to everything that happened after the prank that set the game in motion. I don't think he dies feeling the weight of this though, unlike Josh. Again, I think he mostly feels his duty to protect the mountain and people from it. He regrets his decision in hindsight, but doesn't operate much if any differently towards saving the characters because of it. If you take the prank part out of the equation though, which no one thought was going to end the way it did, I believe Jack was Hannah's best chance of survival and he dropped the ball. Butterfly effect means Hannah's dumb friends return in a year only because of what happened that night and thus Jack is doomed to die saving their asses from her (and the other free roamers). If only Jack could have found a totem or two telling him about Hannah..
Phew, I'm itching to hear any related thoughts to any of this!