Do you think slavery would have been as widely used in the British Empire if King Charles and King James had not benefitted financially from the Royal African Company?

No

Explanation:

Consider, the Royal African Company was founded in the year 1660made a fortune from the slave trade for the British Empire. According to estimates, within a period of just about 69 years (1662 and 1731),  the Royal African Company transacted over 168,000 slaves which were then sold for hard labor and placed in other inhumane conditions.

These slaves had a high demand at the time and so slave traders such as the Royal African Company made thousands of British pounds in profit.