How is Softwalker's legend important in the novel, Wind Over Wisconsin?

At the beginning, a mythical Indian brave, Soft Walker, quietly watches the Marquette and Joliet expedition in its first awed discovery of the territory then called Quisconsin, and the reader is left to fill in the blanks of what happened to Soft Walker's homeland in the following centuries. At the end, the saga returns to Soft Walker's legend, and the realization of what happens to those who cannot adapt to change.