What this teacher says is so eFFING wrong, it boggles the mind. Where does she think the white ship owners gathered the slaves?—from African rulers who had captured them, enslaved them and sold them. Not to mention they had been using slaves well before the white men developed that particular market.
The whites didn’t want to even get close to the African shore, because of insect-borne diseases like malaria. The slaves were brought out to the ships by Africans.