What was one of the main reasons for the popularity of African slavery?

it was because of the sugar revolution in Europe. Sugar cultivation is quite labor intensive, and indentured servants were insufficient to meet the demand for labor. Additionally, the life expectancy of a servant or slave on sugar plantations was quite short; as a result there was a continual demand for slaves to replace those who died. So great was the demand that several stock companies, including the Royal African Company, were organized to engage in the Caribbean slave trade for profit. Many slaves in Colonial America, particularly in South Carolina, arrived by way of the Caribbean islands.

Explanation:

So the sugar market in Europe was the primary reason for the transport of African slaves to the Caribbean.