the argument is like this. if the europeans didn't come and swoop into
the land of the indigenous, the indigenous would still be in their
primitive lives without medicine, security of housing, nutritious food
etc. but since the european boys came, even tho they enslaved some of
them, OVER ALL, we can see that black people live better lives than they
did 500. years ago.
This viewpoint is infected with collectivism, a lot of viewpoints are but most people have not trained themselves in philosophy well enough to spot it. Once I point out the collectivist premise it will seem obvious:
"the indigenous" who is that? What set of individuals is that?
"still be in their
primitive lives without medicine, security of housing, nutritious food
etc"
That gives us a clue as to what the author meant, but you can see that this is absurd on the face of it. Slave kidnapping occurred hundreds of years ago. They would not in fact be in their primitive lives, they would be dead.... of old age if nothing else.
What the author means is the racial collective would still be X. Descendants would still be X. That's true, but blood lines don't have rights and neither sin nor glory is inherited (it is a common ethical error to believe they are).
The evil remains, regardless of what good it may have led to in others be they complete strangers or descendants. "I'm doing this for your own good" is the siren song of the collectivist tyrant.
