A small but growing political party in the United States unafraid to speak truth to power. Once they get a bit larger and more well known by the rest of the electorate, and have a fighting chance to win some elections, I might cast my vote for them.
That's cool. If they have workable plans that speak to the electorate, they'll succeed. Time and experience will tell.
Now, back to reparations. I'm trying to help you out here. You are negotiating. Your going in position is you want compensation for having never been a slave. That's a tough sell. How you handle this negotiation is going to require tact and cunning.
In your OP, you stated:
it is time for the U.S government to finally apologize for the oppressive institution of slavery, and offer reparations to all people of color who were affected by this dark chapter in human history
You want cash but don't state a specific amount. They guy across the table is waiting to hear a number and wondering what benefit will come out of the transaction which you also have not stated. So far, there's not a reason to pull out the check book.
You receive pushback as in any negotiation and your first response is to call the guy across the table a name: supremacist. That's your very first counter offer. How's that negotiation going? Would that work in a board room? Does that counter offer get you closer to a deal? Does it enhance the relationship with the guy with the checkbook?
Now a bit about the guy across the table. He has invested heavily in your cause. Specifically 620,000 killed, 476,000 maimed and 400,000 captured or missing in a bloody 4-year war. America's bloodiest. Every one of those casualties devastated a family and a community. Untold treasure wasted on the battlefield. A major portion of the country devastated which took generations to rebuild. So as he's reflecting on this massive cost in blood and treasure, he's still waiting for a number from you but so far all you've done is insult him.
So you're still sitting across the table from the guy with the checkbook. You've insulted him but he's still sitting there. How are you going to repair and revive this negotiation?
Go back to the beginning. State how much you want. Get the negotiation back on track. Sell the good points of the deal by explaining why this is a win-win for everyone at the table.
If your case is strong, it will sell itself.