What is one reason why slavery developed in the American colonies?
The need for farm labour in the hot climate of the Southern States.
The first effort to raise crops found that the settlers were unwillingly and unsuited to working in the hot climate of the Southern States.
The second effort was to follow the example of the Old Testament of having people sign up to be slaves for seven years, called indentured servants. This effort also ended in failure because the indentured servants often ran away and faded into the general population. The indentured servants were English people that did not differ from the general population.
The plantation owners needed workers in their fields. Black slaves were imported from Africa. These slaves being black could not escape and fade into the general population. The slaves at first could not speak English, so they could be held easily in slavery. The Africans coming from a similar climate were able to work in the hot climate of the Southern States.