Some loose ends, but that's not necessarily bad

Rating: 9/10 (2 January 2019)

There are a lot of reviews here that talk about the multiple loose ends, and I agree with them, but I don't think that the movie is awful just because we don't know what the beings are, where they came from, or why some people are immune to it. We do get to see some kind of gist of what the creatures look like from the drawings that were shown, but that adds to the ultimate mystery of what those things are.
I think of this story as a slice of life story, where they are regular people stuck in the mess and they don't "conveniently" know all about the situation. Just like if a regular person was going through this, after some time you'd know the basics: don't open your eyes, etc. I found that I didn't end up caring where the beings came from or what they looked like, but more about the characters.
If the movie was to also explain where they came from, what they look like, etc. it would be a way different story. The people in this story aren't scientists who need to figure it out, they are random people who need to deal with it and survive.
This story is looking at the aftermath and the toll it takes on people, either in the biggest or smallest ways, than it looking at who, what, where, and why.