Here you and I disagree. The world in 1760 was not today's world. Slavery was predominant in agricultural economies world-wide in the tropics and warmer parts of the temperate zones. The US was neither unique not the creator of slavery.
As the world became more "civilized" slavery was eradicated from most of its areas, although we are seeing examples today in some zones in Africa and, particularly, in Northeastern China. We saw it in the Gulags in Russia and even in the caste system of India less than 100 years ago, in fact.