most important argument for being careful with these issues: it does not matter whether someone deserves reparation in theory, what matters is the public policies that will be enacted in response. And most of those that are proposed are bad for the society and bad for the former slaves.
Here is a simple test to see if someone is sincere: do they support choice in education – vouchers for private schools charter, online – anything that will help at least some poor people to escape bad schools . If they do not (and most unfortunately do not), it means they do not really care about helping these people, but about some other things.