The use of “happy” slaves on currency was widespread in the south. They had to prove to the north that their slaves were “happy” being slaves.
It has sometimes been said that the history of a country is reflected in its money. That was certainly true in the history of early American paper currencies, and the slave images makes a very powerful statement on the contribution of enslaved Black people.
Cotton and slaves were the foundations on which the economy of the South was built. They were important properties proudly displayed on its paper money. Slavery was very important to the South because “It’s right on the money”.