Why is it effective to have the boy tell his own story in "by the waters of Babylon"

Narrative point of view is always an important choice to authors.  "By the Waters of Babylon" makes use of a first person point of view.  By having a first person narrator, the author is immediately limiting the details that are available to readers.  We only know what John experiences, sees, does, hears, and thinks about.  We have no knowledge of anything else until John either experiences it or tells us about it.  An all-knowing, omniscient narrator could potentially ruin the wonder and mystery that this story contains.  When John experiences the "god roads" for the first time and the Place of the Gods, readers experience John's wonder and fear.  His emotions are basically "our" emotions because we are experiencing the story from his perspective.  It is effective for John to tell readers the story because it allows us to have a deeper connection to John's world.  We get to experience firsthand with John, instead of having an omniscient narrator tell us about John and the world.