In what ways does Cather make Jim’s grandparents so significant in My Antonia?

Jim Burden is a ten-year-old orphan who moves from Virginia to Nebraska to live with his grandparents on their farm. Antonia Shimerda, a Bohemian immigrant, moves to Nebraska with her family. Each is challenged by their circumstances to feel at home in the new land.
Jim's grandfather is a hard-working, generous, and religious man. He is a respected leader of the community. Jim's grandmother is a friendly and pleasant woman, devoted to her husband. Together, the couple maintains a beautiful home and a productive farm. On the other hand, the land of the Shimerdas is not useful, and the immigrants barely survive the first winter. Jim's grandparents try to help Antonia's family and bring them food through the winter. However, the hardships are too much to endure, and Mr. Shimerda commits suicide. Jim's grandfather offers Antonia's brother a job on his farm, while his grandmother employs Antonia in the kitchen. Before leaving Nebraska, Jim's grandmother ensures that Antonia gets a job with the next door neighbors.
It is heartening to see the compassion and generosity of the Burdens in an atmosphere where bigotry towards immigrants was common.