I just call them quarter eagles, and the year. I've lived in Colorado, Arizona and New Mexico which all had populations of American Indians. It was only the artsy fartsy people that wanted to be called Native Americans. All of the Indians that I worked with preferred to be called Indians. It is not disrespectful if you say it in a respectful way.
So I think the key thing about Columbus was the fact that he is the one who introduced America to Europe and caused the mass migration. He may not have been the first discoverer, but he was the most important as his experiences had the largest impact.