My impression is that in the British North American colonies there were only indentured servants (of a variety of backgrounds) at first, until later in the 17th century slavery of black Africans became entrenched. Why was this the case when other New World colonies had slavery almost from the beginning?
English common law didn’t have a system of slavery, so they gradually developed it as a result of economic pressures and the spread of the institution of slavery from other colonies. Meanwhile, the French, Spanish and Portuguese already had legally developed systems of slavery based on the enslavement of non-Christians during “just wars,” which were more quickly adapted to the African slave trade. Furthermore, England was generally a little late to the colony game compared to continental Europe, and colonial economies drove slavery.