I agree that these are not typical Native American tribal art subjects nor depictions, especially if one is thinking the chair is old. Many Natives lived in western-style houses, especially when they were trying to "be white" and not lose their lands and religions -- see history of the Cherokee in the east. But the depictions are not that good, nor do they have any power symbols (as one would associate with a chair for an elder or leader).
This is not to say this was not made by a Native American person -- after all, no art form is static over several hundred years, and the skill of many native artisans is as influenced by white culture, European-style art schools, and white gallery owners, as it might be by native customs or traditional symbols. But this would mean the piece is not all that old.
I'm thinking it's more folk art, too.
