It's an interesting point. I'm all for languages evolving as they do. I still would say that the "first" meaning of slave would be known to a majority of people

It's an interesting point. I'm all for languages evolving as they do. I still would say that the "first" meaning of slave would be known to a majority of people as "an enslaved person." For that reason, it seems like using that term should be avoided and corrected. In the same vein, even if a small number of people created an alternative meaning that was offensive for a term, I wouldn't think that particular word should be changed/removed just because of that minority of usage. When the first and most common usage has an ugly history that impacts real people, that seems like a good candidate for an alternative term.