As We Sat Waiting

I am kinda confused in understanding the point of view that this novel is written in. The narrator is clearly there as a part in the action. He uses pronouns like "we" and "I", but he is also sort of "all-knowing". Especially in the beginning when he talks about Lt. Cross and Martha.. "Lt. Cross gazed at the tunnel But he was not there. He was buried with Martha under the white sand at the Jersey shore...he was aware of how quiet the day was...yet he could not ring himself to worry about matters of security" (page 11). How does the narrator know all that? I guess he could just be making assumptions.
This confusion makes me question the actual role of the narrator. Why is he even there? He doesn't really get in on any of the action. When you envision the actual scene, he is just there, listening to Rat Kiley or someone telling a story. Surely he will play a bigger role eventually, right?

Even though he is telling us these stories, I think he is just a flat character. We really don't know him very well other than he fought in the war, and he is now an author. I can sorta create some other personality traits of his based on his description of the other men, but I don't think he will change the course of the story. His sole purpose is to tell stories to his audience.