Well, like I said, the usual US usage of 'racist' has for the last century and a half has included as a major component of its meaning "Bad way of thinking and acting that characterized the attitude of whites, particularly in the southern states, towards people who were members of the groups actually enslaved, or who had been enslaved, or who were descended in whole or part from those who had been enslaved'.
If Droopy wants to use another word instead, he can, but it is unlikely to come into general usage.
And yet a substantial undercurrent (when not overtly expressed, as Samuel L. Jackson recently did) of anti-White, anti-Semitic, and anti-Asian racism exists within contemporary American black culture and is, at present, probably the most persistent and commonly expressed (and accepted and tolerated by elite "progressive" culture) form of racism among us.
As I have tried to make clear, and following Dinesh DeSouza here, slavery in North America and in the South was a transplantation and holdover of the
ancien rigime; an economic, cultural, and traditional practice that had existed from time immemorial among virtually all peoples. Even without the justifications for the practice, based upon the physical characteristics of the slaves, the practice would have existed anyway, as it in no sense required any racial justification. Romans enslaved other Caucasian peoples. Irish enslaved other Europeans. American Indians enslaved each other (and sold them to Europeans, on occasion), and black Africans already had a long history of slaving and slave trading in place when the Europeans came on the scene.
The really viscous racism of the old South was more a product of the destruction of the agrarian serf society the South had created in contradistinction to the non-slave, urbanizing, technologically progressing, commercial cultures of the northern states, than a pretext for the original practice. That needed no pretext. Slaves were the spoils of war, indentured servants working of their passage, members of lesser castes, and natural inferiors doing their part for society (a concept dating all the way back to Plato and Aristotle).
If all the slaves in all the plantations in the old South had been Danes and the slavemasters black, nothing would have been any different regarding the existence of the institution (as the existence of a number of wealthy free black plantation owners holding their own black slaves testifies). Indentured servitude was a white on white institution, and was not too far removed from chattel slavery.
Theories of black inferiority, therefore, were not the pretext for the Atlantic slave trade, but cultural self justification for slavery in the particular Christian and classical liberal context of the Founding, both of which were understood to be incompatible with the practice.
In Africa itself, or in Muslim nations at the time, for example, the question of whether slavery was "right or wrong" never would have arisen