Answer:
The narrator plays a central role in "To Build a Fire."
Early in the story, he points out the main character's lack of imagination.
This is very important, as this lack of imagination will do the man in.
The man makes many crucial mistakes.
A lack of imagination contributes to these mistakes and costs the man his life.
Step-by-step explanation:
The last sentence* is no longer needed because the narrator's identity was revealed earlier when this passive sentence** was changed to active voice.
* The narrator suggests this might be the case at the very beginning of this harrowing tale.
** Early in the story, the main character's lack of imagination is pointed out.