Jamaica was never a place for American slaves, as we well know. In fact, Jamaica was ruled by Spain until 1655, until it became a British colony heavily dominated by sugar plantations. From the start, such plantations relied on slaves for the production of sugar until their emancipation in 1838. I am sure Harris is trying to make voters think Jamaica was populated by American slaves to make them think her ancestors were exploited by bad, bad, America. Identity Politics with a high octane infusion of lies is just what you would expect from someone who slept themselves to the top.
... and is trying to demonstrate their "stree cred" and deflect nasty things that will come out about her time in California state government.