Read up. Read about the people sold to Islands in the Caribbean, Africa and the middle east. They came from Ireland and Scotland. Read about the 'indentured' servants who were never freed after being forcibly taken from their homes, forced onto ships and sold to the highest bidders. What is wrong with that picture? Oh, that's right, they came from Ireland and Scotland, so their slavery doesn't count. Got it.
It very much counts. In fact, it was a part of a larger, systematic and pervasive institutionalized racism in this country.
"Irish need not apply." Do you know that Irish people were not considered "white" in America, by American society and institutions, until late in the 19th century?
But here's the thing. The racism against them that justified their mariginalization, discrimination, (like being denied housing and jobs and having their children placed in Protestant families against their will), it was brief and ended.
The same cannot be said for black people.