There have been MANY people in history who, looking through modern glasses, were racist. Racism was, unfortunately, somewhat "standard" until fairly recently in human history. It's a holdover from tribalism, when people who looked different than you actually did pose a threat. However, we tend to memorialize people based on what they're "well-known" for, or their "claim-to-fame". Winston Churchill's claim-to-fame is successfully leading Great Britain against the Nazi army and Axis powers in WW2, not speaking out against people of a different color. People like Robert E. Lee and Stonewall Jackson's claim-to-fame is being a traitor to the United States, and unsuccessfully leading rebel armies in an attempt to overthrow the US government so that they, and others in the south, could legally enslave human beings.

Based on your logic, the issue of slavery should also be looked through historical perspective as well. Throughout history, slavery was commonplace. So, why decry people that fought to keep slavery in the South, especially long after they're dead?

Why should I only view Churchill as a leader who fought against Hitler? Why shouldn't I remember him for killing over 20 million civilians due to famine he deliberately caused? Churchill wasn't just fighting to save his countrymen; he was fighting to keep the British Empire intact. Even after the war, he refused to give up the colonies and only did so upon pressure from FDR. Your argument here is basically that we should remember Churchill for one aspect of his life, which is clearly wrong.