The following link from the Library of Congress digital collection corroborates our earlier findings on the first 20 or so Blacks in the Virginia Colony -- They were traded as 'Indentured Servants.'

"The first African slaves are brought to Virginia by Captain Jope in a Dutch ship. Governor Yeardley and a merchant, Abraham Piersey, exchange twenty of them for supplies. These Africans become indentured servants like the white indentured servants who traded passage for servitude. John Rolfe to Edwin Sandys, Jan 1619/20, "About the latter end of August..."

Scroll down to the bottom posting on the link to Aug. 1619 --

This is primary source documentation. You simply cannot follow anything but primary source research in your studies. The British did not enter the slave trade until 200 years after the Portuguese and Spanish, who had learned about slavery via their treatment by the Ottoman Empire slave trade of whites.

https://www.loc.gov/collections/thomas-jefferson-papers/articles-and-essays/virginia-records-timeline-1553-to-1743/1610-to-1619/