Is the term "African American" racist towards Jamaicans? Is PC implying that only Africans can be blacks?

Well Jamaica is part of the "Americas" and if they came from "Africa" then I guess it would be correct terminology. The natives of Jamaica were indigenous people and the reason why so many people of African descent live in Jamaica today is because they were brought over by Europeans to be slaves and work in the sugar cane fields. The indigenous people who lived there largely died out from disease brought by the Europeans and although there is definitely a population of them still there, many of them have inter-married or had mixed in with the African descent population that came there via the European settlers.