Amazing that you can blamed one man for the spread of diseases from the old world to the new a few hundred years before the germ theory or blamed the interactions of difference groups in the new world for the next 400 years on him.
footnote the peaceful natives had before Columbus had been doing the same thing as Europeans had IE killing each others in wars and conflicts not to mention groups that have the lovely habit of seizing women and children from surrounding tribes and cutting their still beating hearts out as a token of their love for their gods.
The first settlement in Virginia was wiped out by the peaceful natives and Columbus lost a very high percent of his crews on this third voyage if memory serve me correctly.
Only someone who look at the world in a childlike manner would think of taking the position that Columbia was in anyway or in any manner responsible for the next few hundred years and what happen to those poor so call peace loving natives.
In any case he was a great explorer and a man of his times who for good and evil connected two great branches of mankind that had been apart since the land bridge flooded ten of thousands of year before.