I'm always disgusted by the Kapos behaviors toward their fellow prisoners. These Kapos have also had their freedoms and lives stripped from them, but they are so quickly willing to join their captors and mistreet their fellow prisoners in an even more severe way than the SS officers themselves, all for some extra rations and a few other privileges.
I think another part of what is inhuman about the very beginning of the story is the Jews ignoring of Moshe the Beadle, despite his very earnest and descriptive warnings. Then, in the name of survival, everyone simply doing what they are told. In a way, it was more of an instinctive response to simply follow orders than fight for their lives at the primary stages of their imprisonment. And all of this, because the Jews couldn't believe that anyone else could be that inhuman toward them.
From the historical context of the novel, by the time Jews were loaded onto rail cars for transportation to the death camps, they had already suffered years of abuse, hunger, hard labor and segregation into ghettos. The dehumanization process, therefore, had begun much earlier, and in chapter 2 we are witnessing the end results of that process.
Like any humans presented with such dire circumstances, the body and mind do whatever they can to survive, which in some cases meant going insane and denying reality, or it meant turning into an animal only concerned with self preservation. Night is full of examples of both.
This is a particularly good chapter to look at for the images of inhumanity. The Jews are herded (note that word) into boxcars to be transported to the camps. They're stuffed into this space with no provision for bathroom needs other than a bucket and no food or water. This modest people is pressed closely together, much the way a herd would be. Treating people like animals is certainly a quick and effective way to dehumanize them. There are lots and lots of other examples in this chapter and others; however, I can't leave this chapter without a reference to Madame Schachter--because she's an example of the Jews turning on each other in an inhumane way. She goes a little crazy, as you know, and people are put out with her jabbering. They tell her to be quiet, she doesn't. They scream at her to be quiet, she doesn't. They hit her, she doesn't. They tie and gag her, and she has no choice. Her child was upset at first; however, soon he passively watches as his mother is beaten and gagged. This desensitization is one of the key themes in this story as well as being a method of control by the oppressors.