Question

How does the narrator in top of the food chain help advance the story's theme of thoughtless decisions leading to unintended consequences

Answer 1

He is unreliable, leading readers to question what he is saying.

Answer 2

I believe that it was his unreliability that helped advance the story's theme of thoughtless decisions leading to unintended consequences. The fact that we cannot really believe what the narrator is telling us helped the story proceed its natural course of telling.