When the Spanish missionaries brought their faith to Santa Fe, they lacked the beautiful art that would be a part of a European church. These more primitive pieces were made to fill that void.
I was fascinated by the Santos that I saw in churches and museums. I found the following background information at The Collector's Guide.
Four hundred years ago, the Spanish came to the New World and brought significant changes. One of the most lasting changes was their faith, Catholicism. Santos (painted and carved images of saints) have lived in the homes of Hispanic New Mexican as well as Native American families for hundreds of years. The missionary priests needed "visual aids" to help explain the stories of the saints and the Passion of Christ to the native peoples and used printed images from Spain. At first, some statues were brought from Spain and Mexico but the responsibility for making santos was handled by Franciscan friars and then by local craftspersons and artists, many of whom set up schools or escuelitas. Gradually santeros, the artists who made the images of saints, began to carve and paint the popular saints to supply New Mexican churches, homes, and moradas (village worship space for the Penitente Brotherhood). The santos were made either two dimensionally (retablos), or three dimensionally (bultos).