You are referring I presume to the $300 compensation each slave owner was paid for the loss of the slave due to the Emancipation Proclamation signed by Pres Lincoln? That was not "reparation" as you've described it, it was gov't sponsored payment/compensation for lost personal property due to gov't action. There has never been any formal "reparation" paid in this country to anyone other than a slave named Belinda Royall in 1783 in the form of a pension.
And to even bring up the incident with Harriot Tubman shows your true intent. That is a single incident much like another slave stubbing their toe, or being thrown from the farm mule and breaking an arm, or being run over by a runaway team. These are not valid arguments, just examples of incidental things happening at a time in history when it was considered common. Was slavery valid, hell no, but then you must ask yourself how did all the slaves get here from their native lands ... actually ask how many were sold into slavery by their own kind or their own tribe from their own native country.
Throughout history of civilization, one man's house was built on top of another man's cave ... one man's village was built on that man's house ... one man's town was built on that man's village ... one man's city was built on that man's town, etc, etc, ... each one built by the victor over the weaker. Were any of them right or even acceptable, it depends on the time in history of it happening and one's own perception. But I'm pretty sure you know that, you just don't like it. And that's OK to not like it ... I don't like some of it. But we all have to accept it and move on. The answer is to see it never happens again rather than to keep opening a sore that needs to heal.
I'm not by any means supporting slavery of that time nor anytime. But it has been a natural and common part of life for many nations and people over the history of mankind, regardless of color or homeland. The fact is it still goes on today around the world when one tribe overcomes another tribe. To blame the USA or any other country for actions which at one time the majority of the world accepted as right is evidence of a very slanted viewpoint seeing it only as they prefer, and much less a viewpoint of the real world as it is now/today! That same person will often also not recognize the benefits and opportunities that this country has made them and I've not ever heard anyone say they would be willing to go back to the life where the slaves came from.
I personally will never be held responsible for any activity that happened prior to the late 1940's, nor will I ever agree that anyone today is in anyway responsible for it. Neither will I accept that anyone who today claims they're entitled to anything from that time in history deserves it, with a very few exceptions. I assure you I know plenty about slavery!!!