Would you consider Annihilation (2018) a horror movie?
I wasn't scared by the movie, but it has a similar dread throughout the movie. There are also some jump scares, and the ending has that 'evil didn't really get defeated' quality.
It's certainly not jump scare horror; it's more existential.
I enjoy horror movies, but they've long since stopped "scaring" me. To me, they're mostly just fun -- seeing the effects, the ways they'll put their own twists on genre tropes, etc.
Annihilation, for me, invoked a true sense of dread and, well, horror. It's several years old but still lingers with me.
(After writing this I realized you said 2013, not 2018... hope that's just a typo and we're talking about the same movie)
Yeah it isn't scary, but I'm kind of desensitized to scares these days. Talk to Me was a good movie with some prefictable cliches but not scary. There was a similar dread about what was going to happen that had me tense in some parts though.
I think my criteria for if something's a horror movie is answering this question: is it trying to scare me, or otherwise make me uncomfortable? If yes, then I think it belongs in the category to some degree. A lot of angst is spent by genre fans (horror especially, I've noticed?) wondering if something belongs in the genre, and I personally think a lot of it is unnecessary.
Enjoy what you enjoy, and if it spooks ya then I think it's fair to at least say it has horror elements.