Why was slavery in the United States a paradox?

Freedom and slavery, the 'central paradox of American history' In October 1705, Virginia passed a law stating that if a master happened to kill a slave who was undergoing "correction," it was not a crime. Indeed, the act would be viewed as if it had never occurred.

Slavery in the United States was a paradox because the Constitution states that all men are created equal, yet the same document allowed for people of color to be enslaved.