There are a lot of themes at play in this movie, many of which are still as relevant as ever, as I *think* it's primarily examining the different aspects of being an "ally" and the implications of how an ally can inherently always choose to side with the oppressor and retreat into their own privilege.
That being said, I'm not entirely sure that I'm right about that - I imagine a lot of the meaning here's in the eye of the beholder, which characters they find themselves identifying and/or sympathizing with, etc.
Point being that the strongest thing about this film is it tells a super engaging story that deals with really complex, important issues (capitalism, racism, imperialism, alienation, allyship, what retribution might really look like, etc.) without dumbing it down to the point that it's spoon-feeding you things like "who is the good guy?" or "what should I take away from this?" or "how should I feel about anything that happens to any of these characters?"
And I mean that in a good way - I'm not confused because of indifference, but because there are challenging things about every character and nearly every choice each character makes.
I don't know if I'd even consider it a horror movie. I mean, I don't know what else I'd call it, but - and I'm saying this as a major lover of horror and a deep believer in all of the different ways it can be used - I feel like it's a bit reductionist to label it as horror. I was never scared, any violence and gore is visually underplayed (deliberately). I guess I'd consider it folk horror, but in the same way I'd say the original Wicker Man and Deliverance are folk horror - like Wicker Man is also a musical comedy, Deliverance is also a survival thriller, and for whatever reason those are the two movies of which I was most reminded by this. For context, the original Wicker Man is my favorite movie, so I don't use the comparison lightly.
But yeah, suffice it to say - great movie that you should definitely watch.