It’s a great script and I hope it wins Best Original Screenplay Oscar (and JoJo Rabbit wins Best Adapted Screenplay).
The thing I noticed confirms my take when I watched the movie: The story shifts from Drama… to Thriller… to Horror. It does so seamlessly based upon events which occur, but importantly personality traits and dynamics which exist within the characters of Ki-taek’s family. Their potential to do what they do is there from the very beginning. Fascinating and engrossing story.