It's been near 15 years since I read it, but it's kind of a cautionary tale about tradition, superstition, and how easily humans succumb to their base impulses and can commit insane violence.
The qualifier base is exactly right. Like we use base as a pejorative, but it is what we are. That is our base state.
You know what itd take to drop us back to this level? I would say about a week without electricity. If you said to any given group of what, 50 people. Pick numbers out of a hat. The person with the dot dies, but the electricity comes back on. That would be enough.
It's supposed to make you feel very weird because it is innate tribal behaviour that is not very far from the surface. Individual vs group, traditions, rituals, sacrifice, and the perverse gratitude that you are the survivor etc.
Read it then go read Facebook for a bit...you start to see people for what they are. Panicky, social, tribal animals.