American colonists from European cultures viewed both Africans and Native Americans as substantially different in many ways. Culturally, of course, both "Indians" and Africans were viewed as from totally different backgrounds and had totally different views of the world. How the two non-Eurocentric groups were viewed was quite different, and varied by region.
Native Americans were viewed as human beings with a differing cultural perspective from the first in the Southern colonies. Virginian William Byrd (1674-1744) wrote that "the best ambassador is a sprightly lover," as one of the justifications of intermarriage as a means of understanding and keeping the peace. In New England, on the other hand, at first there was a debate as to whether or not the natives were human. The Massachusetts colonials decided in the end that they were not, and had no souls. Interesting, when one considers that neither colony would have survived without aid from the native peoples.
Africans were a different matter. Europeans had had contact with Africans since Roman times, even black Africans from the interior. Archaeology has discovered that there were great cities in the interior of Africa (not simply Carthage, Ethiopia or Egypt) long before Rome, but those cultures had disappeared long before contact of any sort with Europeans. Black African cultures were mostly quite primitive outside of Ethiopia and Eritrea, and consequently were often viewed as inferior. Blacks were first brought to the colonies by the Dutch to Virginia and traded to the colonists, but were treated as indentured servants and set free with pay and/or land after (usually) seven years. The concept of slaves as chattel property in America, ie the equivalent of furniture or cattle, began in Massachusetts in 1644. To justify this, a doctrine of black inferiority was developed, again in the Northern colonies rather than the South originally. These concepts (chattel slavery and racial inferiority) spread throughout the colonies.
African-Americans played an important role during the Revolution, not only as soldiers but as spies. Throughout the war George Washington personally ran one of the most successful spy rings in military history, largely consisting of blacks who worked as personal servants of British officers, including the generals commanding the British forces (Howe, etc.).
There were many free blacks in America during later colonial times (and in the South all the way to and through the Civil War). Crispus Attucks, killed in the Boston Massacre, is perhaps the most famous. There were also non-African slaves in the colonies, including Carribean "Indians" and some whites, largely from Scotland, kidnapped and sold in the aftermath of the Jacobite rebellions of 1715 and 1745.
The primary similarity between how the colonists perceived the Native Americans and how they viewed the African-Americans springs from their respective places within colonial society. Neither Native Americans nor African-Americans fell within the mainstream of colonial society.
While Native American culture did have its admirers, Native Americans, in many ways, were viewed as culturally inferior to colonists because their culture did not coincide with what existed with colonial society. Much the same could be said regarding those who came from Africa beginning in the early seventeenth century. In the Southern colonies, on the other hand, African-Americans lay outside of colonial society in that the majority of them were brought to the New World as slaves. Colonists did perceive Native Americans as people with different cultures and cultural values, but they tended to view slaves as property, a factor that automatically precluded them from being members of colonial society.
Much of the difference between how the colonists treated Native Americans and African-Americans derived from the role that each served within colonial society. Native Americans were seen as having very little real contact with society and were often treated as second-class citizens, while African-Americans were seen as either second-class citizens in the North, or property in the South.