One attitude was that blacks were not really human, they were animals that needed to be coerced into working to get anything useful out of them.
The other attitude was that blacks were human but were childlike and could never survive on their own. They "needed" the institution of slavery to make them viable. Whites were actually "helping" them survive.
Both are totally ridiculous when you look back on it but judging 19th century people by today's stds will give you a very distorted view of history.
a good synopsis of the racial views of the mid 19th century.
I think that well before the rebellion there was a third category which believed that slavery was wrong and blacks held as slaves should be freed and could make it on their own, but also subscribed to the belief that even so whites were superior to blacks and integration of the races was not necessarily a good thing. Likewise ridiculous by our current day standards, which is why people of the period shouldn’t be judged by current day standards.
A nice summation though there was one other group, albeit very small. The radical abolitionist, such as William Lloyd Garrison, who did believe in total equality between the races. They would be the only ones not considered racist by today’s standards.