How were the relationships of Britain's and American's colonists with American Indians and African-Americans during a colonial period?
This is an interesting question! The relations of white colonists in the British colonies was very different to these two groups. The Native Americans were totally new to the colonists, and they were generally regarded as handsome people and intelligent. They were definitely "different", but not quite so exotic in some ways as Africans. One would think that white Europeans would have been somewhat more used to blacks, since Africans had been seen in Europe often for hundreds of years. But a great many had been Muslims during the invasion by Islam of Spain and France. The African slaves brought to the New World (first by the Dutch and then the Spanish) were largely from more primitive cultures of eastern Africa, not Muslims.
The blacks brought to America were from stone age cultures, and so were viewed as unsophisticated and, inevitably, inferior. As time went by and blacks in the New World became "civilized", this did change, but Europeans had a nearly inassailable sense of themselves as superior to other peoples. They viewed everyone else as human, but somehow inferior. In general, there was a sense that the "dusky races" were less intelligent.
Native Americans were viewed somewhat differently. Despite the fact that the Massachusetts colony would have perished if not for the help of the native people, they were viewed by the Puritans as not quite human, and as not having souls. Whites who were unusually friendly or who had serious social interaction with the natives were considered corrupted. In the Southern colonies, as a colonist named Byrd wrote, "the best ambassador is a sprightly lover." Marriages (legal and otherwise) became relatively common quickly in Virginia, although marriage between a black and a white remained frowned upon North and South through most of American history. Viewing the Native American as a relative equal in humanity, however, did not in any way keep the whites from despoiling them of their land and culture.