I suppose the Natives can start a revolution to take back what is perceived to be taken unjustly, just like how every bit of land had changed hands. I suppose I can claim a good portion of the Earth based on ancestry, since everyone is descended from an original small group of ancestors. How far back should you want the argument?
No one should be held accountable for the actions of those that came before. I am Swedish does this mean I need to be held accountable for the actions of the Vikings? Are all Germans responsible for the holocaust? Are all Muslims responsible for Islamic Terrorist.
Not only are we not responsible but the fact of the matter is the Natives were conquered. They lost. If we were to give them land back why would we stop there, why not give all conquered land back to those who originally inhabited it.
Although some of the tactics that were used were horrible, it is wrong to say that we should all feel so horribly about it and give back. The Indians had been doing it for hundreds of years before the white Europeans had got there and in every culture around the world throughout history. The Natives also committed horrible acts and broke treaties. In the end white Europeans won and should not have to pay retributions for it now.