Why and how were Africans captured to be slaves?

Africans were used because they were partially immune to tropical diseases like malaria and yellow fever. The Europeans would have preferred to use natives on their New World, but they kept dying on them. So they shipped in hardier stock (PS if my Wording sounds harsh, whatever, it's just true from overseas.

The Africans captured were from unorganized tribal villages along the west coast; easy pickings for the slave traders. They were simply forcibly abducted, sometimes entire villages, but more often only half the village, so the remaining people could give birth to more future slaves.

THEY WERE GREEDY AND WANTED SOMEONE TO WORK FOR THEM.

Americans perception towards the Africans at this time was that they were property. The Americans viewed the slaves as a better source of labor. They also viewed the slaves as having no rights.