The term "slave" refers to a sense of possession and dehumanization.
A slave is different than a servant; the term slave implies that they are owned. It is also accepted that the word slave (at the time) justified the harsh treatment they were given. In the eyes of their owners, they were animals. That was the message spread during the time of slaves. Books like "The Heart of Darkness" exhibit this limited and negative view of Africans in general, not just slaves. This view was reflected in culture, in economics, and in religion. Slaves are not entitled to the same humane rights and have no more standing than a horse, oxen, or any other animal that was used to profit and make a living. It also sadly exemplifies how close-minded the world can be, it happens in all cultures all around the world. It reflects human nature.
So, the Constitution's framers heeded Thomas Jefferson who argued: "A bill of rights is what the people are entitled to against every government on earth, general or particular, and what no just government should refuse, or rest on inference."
