A slur or description of painted body decoration(s) of the days?
[This comment was removed]
Many of the Indians first encountered by early settlers (central east coast) used red paint/dye as decoration(s). Probably the initial reason for the moniker, and probably later used to describe all/any natives. The very title Indian is faulty/ misrepresentative, and could be construed by both parties, American and/or citizens of India, as insulting.