How is the theme inhumanity represented in the hunger games?

The whole idea of the story is about different human reactions to different problems we face in life. It is all about how some people are pessimistic and some are optimistic. In other Words, either the glass is half-full or half-empty. The book has a very psychologial aspect to it.

Lemme give you an example.

Throughout the series, Katniss Everdeen is very pessimistic, she never believes that she can win the Games and she never believes that she can be safe.

On the other hand, Peeta Mellark is always very optimistic, he is always the one to cheer everyone up or charm an audience.

Then you get people like Finnick Odair, who has a pretty changeable character. When his love, Annie Cresta, is captured, Finnick is really pessimistic and he keeps on thinking that he won't ever see her again. However, when he marries Annie, he is really happy and he is very social and active.

These are just some of the examples in the book. To understand it fully, I think you need to read it or if you've already done that, read it again.