This country was built on the backs of slaves and indentured servants with a good helping of wage theft and outright theft of land, money, and mineral resources. You really do have a Pollyana-ish view of the natural order of things.
This is a common refrain of the anti-capitalist, anti-American historical revisionists.
Slaves produce little because they are forbidden to act on their own judgement, pursue their own goals and values, and keep what they earn. If slavery were the source of prosperity, human history would have been one long economic boom up until the liberty of capitalism and the industrial revolution. Slavery held this country back. The innovative chemist and agricultural giant George Washington Carver—a former slave—contributed more to American prosperity as a single free man than all of the plantation slaves combined. How many Carvers—and ambitious black men and women generally—failed to flourish because they were locked up in the slave system? How much better off would America be today had this country’s Founding ideals been spread to everyone at its beginning? The loss to this country in terms of today’s prosperity because of the existence of slavery is incalculable.
To say that this country was "built on the backs of slaves" is a grave insult to the memory of the slaves. This country was built on liberty, property rights, and individualism, which benefits everyone, including the decedents of American Indians. It was only to the extent that people were free, not enslaved, that this country prospered.
America replaced a mostly open, uninhabited continent—punctuated by pockets of primitive tribes—with a thriving, life-advancing industrial civilization. Despite injustices against the Indians, which did occur and we shouldn't minimize, the land wasn't stolen. European settlers had as much right to settle in North America as the American Indians had before them and as new immigrants have today. There were also injustices by Indians against the settlers. What the more intellectually and philosophically advanced Europeans brought to North America was a vastly improved continent for everyone, legally, economical, politically, morally, and culturally. They replaced the existing order of tribal tyranny, destitution, and slavery with the benevolence of individualism.
As to so-called "wage theft," there is no such thing. Wages are based on voluntary agreements between employer and employee. There is no theft. Then again, maybe there is such a thing as "wage theft"—minimum wage laws, which is theft perpetrated against the employer; as well as would-be entry-level workers, who are robbed of the chance to get on the lower rungs of the economic ladder of experience and advancement.
Today's State of the Union—The Fulfillment of Obama's Promise to "Fundamentally Transform America": The Legitimization of Freeloading
Notes, and Myths, on American History - 1
The Capitalist Manifesto—Andrew Bernstein