One example is the growing importance of native people among historians. For generations, Columbus was considered the discoverer of America, yet he never touched the mainland; rather, he made it to Hispaniola.
This view of history does not take into account the thousands of native people who already lived in the Americas and their flourishing culture. Native Americans had trade routes, architecture, languages, and religious rites that were every bit as advanced as those found in Europe at the time. As historians, archaeologists, and anthropologists work together to learn about Pre-Columbian societies, they are discovering that the historical narrative of America is incomplete without telling these stories.
Another example of why the memory of Columbus is tainted is the five-hundred year subjugation of Native Americans that dates from Columbus's arrival in 1492. Columbus enslaved the Taino people and made plans to exploit the islands. He forced many to convert to Catholicism and did his part to squelch native culture. He also did nothing to help his own place in history, as he was a poor businessman and was generally disliked by his own crew for being a religious zealot. Columbus opened the floodgates for European monarchs to use the New World as their own personal supply of raw materials.
Columbus, though holding an important part of American history, actually failed in his mission of discovering Asian spices. By focusing on Columbus, historians have forgotten that American history existed well before 1492. Many people choose to celebrate "Indigenous People Day" on Columbus Day.