This is a question that is still rather controversial. It is not completely clear how whites in America saw Africans in the early 1600s when they were first brought to the New World. It is not clear how slavery and ideas of race interacted with one another from that time until 1800. If you have time, you might consult one or both of two books by Winthrop Jordan on this general subject. There is a longer book of his which is a classic in American history. It is entitled White Over Black. He also wrote a shorter book on more or less the same topic. It is entitled The White Man’s Burden.
Jordan’s general argument is that, over the years, attitudes about race and slavery evolved together. He identifies two main starting points for this evolution. One starting point was the fact that there was an economic “need” for slaves (or other unfree workers) in the New World. The second starting point was the fact that “black” Africans and English people were so shockingly different in so many ways.
Jordan emphasizes that the color white was connected with purity, and the color black with iniquity, in English society even before there was much contact with Africa. This connection, along with the tremendous differences in religion, material circumstances, and culture led the English to perceive that they were qualitatively different from the Africans.
Gradually, the conditions of these two starting points worked together to create the attitudes that existed in 1800. The need for unfree labor (and the lack of sources for that sort of labor other than Africans) led to the creation of a slave society. The whites’ general attitude that blacks were very different helped cause them to see blacks as ideal slaves. The two institutions of racism and slavery grew together and reinforced one another so that, by 1800, the slavery and “blackness” seemed to go together almost seamlessly.