Question

We fought a revolution for "life, liberty, and the pursuit of happiness" because "all men are created equal." yet the united states remained a slave nation for over 80 years after this revolution even though some founders disapproved and some states abolished the institution. so, was this great country of ours founded on hypocrisy?

Answer 1

Perspective on who was entitled to the rights.

All of the Founders agreed that white, land-owning men were entitled to the rights of the Constitution. Beyond that group there was disagreement. Therefore, to get the passage of the Constitution some made compromises knowing the states could adjust laws as needed. 
Blacks were not considered people in some cases, let alone entitled to rights. Women also were treated in a similar way. As the US grew so did the groups included in the democratic process.