The discovery of the Americas was a top event in the history of the world. Through Columbus the Europeans discovered the Americas and through the Europeans the rest of the world eventually learned of the Americas, too. Through Columbus the American Indians discovered the Europeans and were brought into contact with the rest of the world.
The Vikings had discovered America, too, but that did not take. Columbus set in motion the events that brought such a significant part of the world, the two American Continent, into contact with the rest of the human race.
This is what the holiday is about.
While considering the faults of Columbus, one should consider the faults of other men of that time, including the faults of the American natives, too. The savagery of the natives and to the savagery of the colonists had two attributes to compare: one the intensity and two the outcome. To say that the natives were nicer than the colonists seems more due to current prejudices of political-correctness than the historical record. The outcome of the colonists’ savagery certainly was far superior to the natives.
Columbus’ bad actions against the natives were still wrong.