Slave labor was only one component of practically all great countries/empires. The West was the first to outlaw it.
The US in particular was built upon the hard-earned lessons of the past, including the moral worth of individual liberty.
This just sounds like more American exceptionalism that most of the world is tired of, and that includes many Americans.
Got an answer to my first sentence?
Louis XIV: "I am the state."
US Constitution: "We the people...secure the Blessings of Liberty"
That's no cosmetic difference.