No, he was far from the first ruler to step down from power. The Romans had quite a few citizens that were given near unlimited power, by being named dictator, and stepped down from it. In times of great crisis in Republican Rome the Senate would elevate a prominent citizen to the rank of dictator, giving them the final say in all matters of state for a year, and it wasn't until the civil strife of the 1st century BE that anyone was dictator for life, first Sulla and later Julius Caesar. Though it should be noted that even Sulla stepped down after he completed his goals.

Cincinnatus is go to example of for a leader stepping down from power, immediately resigning from the dictatorship on two separate occasions after he dealt with the issues that led to his appointment as dictator. Washington is frequently referred to as the American Cincinnatus because of the similarities in civic virtue.