This is a convo more suited to the Root, but your third & fourth sentences are false.
Until the United States was established , the 13 mainland colonies were an extension of the
British colonies in the Caribbean. They were all British territory and the the delivery of enslaved people flowed from Africa to 13 colonies directly, as well as from Africa to (British controlled)West Indies and eventually to the mainland (British controlled) 13 colonies. And as you pointed out from 13 colonies to British controlled West Indies.
The segment of the 1619 Project about Sugar hammers this point home.
But it's been covered multiple times in the Root.
After 1807 , outside of the illegal trade, and whites fleeing the St. Domingue revolution and using legal loopholes to bring their enslaved here, the amount of enslaved arriving here from Caribbean was minimal. The enslaved Africans from Haiti who arrived in Louisiana and other American cities where white St. Dominguans had fled would have been among the last large number.
And even then, American legal system challenged the rights of those planters to import slaves into America
Your sources please.