"The first slaves were in America in the 17th Century." is just another myth as well.
The first slaves to make the Atlantic crossing to North America were most likely Irish. They began arriving in the late 10th century and remained in the general area of the Davis Strait and Labrador Sea for the next four hundred+ years or until just a century or so before Columbus.
They were called thralls by the their Norwegian and Icelandic masters. They (almost certainly) had the blues but no music remains, so... nevermind.