Pretty decent. Chances are you will never be a slave
This is only maybe true (things are changing fast, and mostly for the worse), and only if you define slavery in the worst way, i.e. chattel.
and never meet one which is the only time in human history this has been true.
I've met people who have spent time in prison, given little option but to labor for pennies a day. Not hard to find at all. Slavery isn't even forbidden in the U.S. Many others arguably fit the definition of wage slave. I myself feel compelled to sell my labor, what are my options?
Japanese interment camps. Your argument is defeated
Not sure exactly what you mean by this, but assuming you're providing a counter example, a single instance of something doesn't demonstrate that it is the only way a situation can play out.