Land is not a birthright and ownership, of anything, is not unassailable. Our world, our different cultures, human interaction in general is still very much based around the fundamentals of natural selection. Of course it's rather easy to deny this when you look at modern society and the structures that have been developed to help the less fortunate, but if you were to peel away the multiple layers of our social evolution, you'd find natural selection still very much at work.
People only help others when they can personally afford to do so, in other words, life is still an 'everyman for himself' prospect and those that we take from, in whatever guise that theft is presented, only have the circumstance of life itself to blame, not the thief.
We don't blame lions for being lions, or lamb for being lambs, we don't blame any animal for acting as nature would have that animal act, so how can we blame ourselves, or hold ourselves accountable for being greedy, murderous, kind, loving, treacherous. That's who our animal is.
Of course we don't owe reparations.