How are the themes of innocence and discrimination introduced after Bruno’s father tells him the people seen from his bedroom window are “not people at all."?

The theme of innocence is made apparent in Bruno's question. He sees "people" wearing pajamas..... young boys his own ago. Bruno's father, however, sees prisoners..... animals being prepared for the slaughter. To him, the Jews are not human, one of the reasons he finds it so easy to pen them up and cast aside their lives.