If the question were to take into consideration public school education, I have two modest suggestions: 1) Allow simplifications to foster for youngsters and increase complexity with age 2) Encourage multiple perspectives, including the population with whom Columbus and his men did not treat so well. One could incorporate either (or both) without conceptually ripping it all to shreds. I think most people agree with that. Conservative traditionalists and multiculturalist liberals mostly bicker about the fine details of such matters. Actually, if you looked closely at a meeting with...who was it..Chester Finn and I want to say Diane Ravitch (could be wrong) in the mid-1990s, you could quickly see that both agreed in principle, but nevertheless found each other in a verbal brawl over who was destroying American education with politically correct sentiment or wanting to ensure that contemporary racial and ethnic minorities didn't have a voice. Anyway, the younger the student, the more apt I am to accept the need for mythology in American public schools. I'm a nationalist and I am also of the mind that sometimes acting like the no-longer-enchanted child spoiling Santa Claus for his classmates isn't inherently beneficial. That being said, with age comes the necessity to challenge young minds, and as such, we can slowly delve into more uncomfortable questions.
For the public at large, these pedagogical limitations have less relevance. The adult ought to be able to handle the notion that, say, Thomas Jefferson's incredibly likely sexual relationship with Sally Hemmings would at least in part, be reflective of the inherent: 1) relationship between owner and slave 2) societal perception of white male on black woman sexuality 3) likely cause a series of conflicting feelings when romance may become involved.
Portrayals of past men and women as Satan-incarnates are often far off the mark, but that doesn't likewise prevent us from seeing men or women as participating in great evils (or being the master of great evils).
With Christopher Columbus the temptation is to save, rather than condemn, because he has become a patriotic and nationalistic figure for our American mythology. With another country's figure, we often have far less restraint in concluding them as figures to essentially hold in contempt.