Just goes to you show that you need to be careful what you take as fact.
The earliest known appearance of the term in print occurred on October 9, 1813 in an article quoting a letter dated August 27, 1813 from a gentleman at St. Louis concerning an expedition being formed and to be led by Gen. Benjamin Howard to "route the savages from the Illinois and Mississippi territories[.]" "The expedition will be 40 days out, and there is no doubt but we shall have to contend with powerful hordes of red skins, as our frontiers have been lined with them last summer, and have had frequent skirmishes with our regulars and rangers."[7]
However, linguist Ives Goddard has stated, "When it first appeared as an English expression in the early 1800s, "it came in the most respectful context and at the highest level," Goddard said in an interview. "These are white people and Indians talking together, with the white people trying to ingratiate themselves."[8] It was not until July 22, 1815, that "red skin" first appeared in a news story in the Missouri Gazette on talks between Midwestern Indian tribes and envoys sent by President James Madison to negotiate treaties after the War of 1812.
The term derives from the use of "red" color metaphor for race following European colonization of the Western Hemisphere, and one of the earliest known citations of its use is by a Native American called Chief Black Thunder [9] in which he stated:"My Father—Restrain your feelings, and hear ca[l]mly what I shall say. I shall tell it to you plainly, I shall not speak with fear and trembling. I feel no fear. I have no cause to fear. I have never injured you, and innocence can feel no fear. I turn to all, red skins and white skins, and challenge an accusation against me".
Although initial explorers and later Anglo-Americans termed Native Americans light-skinned, brown, tawny, or russet, according to historian Alden T. Vaughan, "Not until the middle of the eighteenth century did most Anglo-Americans view Indians as significantly different in color from themselves, and not until the nineteenth century did red become the universally accepted color label for American Indians."[10]
It is argued by sociologist Irving Lewis Allen that slang identifiers for ethnic groups based upon physical characteristics are by nature derogatory, emphasizing the difference between the speaker and the target.[11] However, Professor Luvell Anderson of the University of Memphis, in his paper " Slurring Words ", argues that for a word to be a slur, the word must communicate ideas beyond identifying a target group, and that, slurs are offensive because the additional data contained in those words differentiates those individuals from otherwise accepted groups.[12]