What arguments did pro-slavery writers make? Why did they question the ideas of the Declaration of Independence?

They believed slavery was necessary for the economy, "if no one is providing physical work for free, how are we supposed to maintain our multiple mansions?!". some also thought that black people were genetically inferior to whites, and it's only the natural order to enslave them. they didnt exactly question the dec of independence, they just interpreted it differently. pro slavery writers assumed life, liberty, and the pursuit of happiness only applied to them, and enslaving people was a way to fulfil these rights. it all boils down to the fact that they did not see black people as humans, rather property, animals, or investments. yikes.