People in Africa were already slaves; they were made slaves by black people.
The first legally recognized owner of slaves, under common law, in what would become the United States was Anthony Johnson, a black man.
Until Anthony Johnson, white people purchased African slaves and treated them instead as indentured servants, who would become freed men with their own land after a certain number of years of service; white men, such as the Irish, were also indentured servants in this way. White people were the last ones into the slave trade, and white people were then the ones who ultimately ended slavery.
So, yes. There was slavery, but you never get taught the whole story.
It sounds like you're trying to lay all the blame on slavery on black people. Yes, there was slavery in Africa, but the practice expanded greatly because of white Americans. Also, saying Anthony Johnson was the first legally recognized slaveowner is tricky because his case against a slave was the first ever brought to court even though he was not the first slave owner. There is plenty of evidence of slavery before Johnson.