Although the society is clearly made up of people in this book, you can certainly argue that it has been dehumanized. This is because the society has taken away much of what makes people humans.
You can argue that people are human because they think and they feel emotions. Without those things, they would just be smart animals. But both of those things are taken away to some extent by this society.
By banning books and by encouraging people to be entertained all the time, the society is taking away people's ability to think. Beatty even talks about this when he talks about how books got boiled down to little summaries and finally to nothing -- it is largely about discouraging people from thinking. At the same time, they are discouraged from having emotions because they are not encouraged to have quiet time alone with other people. Instead, they are always watching the walls or doing things like that.
So, by banning books and promoting "entertainment" the society takes away the things that make people truly human.