No, and not by a long shot.

Africans (which of course is an extremely vague term encompassing thousands of ethnic groups who happen to occupy the same massive continent) have been getting enslaved at least since the time of the Roman Empire. Likewise, centuries before the discovery of the Americas, there existed a large scale slave trade between eastern Africa with the Muslim world and India. These slave exportations are in addition to the internal slave trade in Africa between the various kingdoms and tribes.

As for the Americas, North America was not the first place slaves were sent, nor was it the largest importer of African slaves. The colony of Brazil alone took in more slaves between 1500-1800 as did the entirety of North America. A similar number of slaves also ended up in the Caribbean working largely on sugar plantations. The Spanish mainland colonies relied much more heavily on the indigenous populations for labor, but African slaves nonetheless appeared there as well.

North American slavery followed this long history of African enslavement, and in some ways was worse than its predecessors. It has the distinction of being one of the few self-reproducing slave populations, allowing the number of enslaved individuals to increase through the generations even after the end of the slave trade. Chattel slavery was the norm, rather than a less common exception in North America, and it is possible to say the no one has ever developed a keener sense of racism than North American whites. But this was not nearly the start of African slavery, just a terrible evolution.