Some thoughts

Why do you think Erdrich chose to write her novel in the way she did, using time leaps and a series of different narrators to recount their own tales? What do you think is gained by this form of narrative? How might the form's emphasis on individual storytelling relate to the novel's larger themes?

I think that Erdrich uses different narrators to make the reader discover the "whole" story from each protagonist point of view. It could be a mosaic of stories and personas, each with their own sets of beliefs, feelings, stories and time frame. Their lives and stories are interrelated yet individual.

As to time leaps, it seems to give a different perspective, as in films with flash backs, for instance, thus the reader can be transported in various eras and also events.

It is also possibly a technique used to captivate the reader.