You are thinking of indentured servants not slavery, a completely different thing.
Slavery was not a way to US citizenship, it was a death sentence on people kidnapped from their own land and forced to work till they dropped. If you disagree, find me the statutes that laid out a path to citizenship for all African slaves in 1790. Were the Jews in ancient Egypt just working their way up to citizenship too?
As for your comment that US citizens who do not think the Constitution is relevant to modern America should leave, you are reneging on the articles you claim to hold dear - freedom of speech for eg. Though given your replies so far I should not be surprised by your hypocrisy.
If you want a rational argument about this instead, please tell me why I should listen to slave owning rapists for my guidance on civil liberties and human rights.