Mike, you make a very good point. While I do consider the first two Halloween movies to be a perfect experience when viewed together. I could assume that the reason no one has mentioned any slashers is because for a while they became kind of synomnyous with “horror movie” and that would just be too easy. Also because despite how many times they came back. The bad guys in those movies could always be defeated. Even though they were masked and therefore lacking identity, they were still human.
And while humanity is a major factor in all of these stories. I would say that the deciding factor, for our choices at least, seems to be in the endings. None of the movies picked have clean happy endings. 28 Days Later and Alien have the closest to happy endings but even then the world is still kinda fucked. *SPOILER ALERT* Rosemary’s Baby ends with her being right, The Thing ends with you not knowing if the last two guys standing are human, and Night of the Living Dead ends with the hero being blatantly shot. The dour ending is apparently what seals the deal. I think it’s cool that we watch movies to feel and I think that’s what makes horror movies so effective espeacially when they down have happy endings. It’s nice to leave the experience relieved but when it keeps you thinking clearly the movie sticks with you.