What the h*ll is this person doing as a teacher in a school?
In a world of war and might makes right, the Indians were overrun by a superior civilization. They made war and enslaved each other. They engaged in cannibalism, torture, human sacrifice, body mutilation etc. They got their asses kicked by a stronger civilization: Europe. This sanctimonious whining about Columbus is a desparate attempt to get emotional reparations.
So let's agree there was slavery and war and disease on evryone's part and the Indians lost. Now what!