Christopher Columbus was a pretty horrible person, so I have no problem ceasing to honor him with a national holiday. But he was also a uniquely important historical person whom everyone should know about, and the well attested date of his arrival, in 1492 CE, should also be something that every educated person knows.
Columbus was not the first person to make contact with the Americas after the arrival and dispersal of the predominant Founding populations of the indigenous people of South America, Mesoamerica, and most of North America around 14,000 years ago from Beringia where these populations had an extended sojourn in their migration to the Americas from Northeast Asia. They arrived with dogs, but no other domesticated animals.
There was at least one small progenitor wave of modern humans that reached at least as far as New Mexico before them about 21,000 or more years ago (as recent research has confirmed this year from earlier less definitive data), but unlike the Founding population of the Americas (itself derived from a genetically homogeneous population of less than a thousand Beringians), they left few traces and had little, if any, demographic impact on the Founding population that came after them, or had only the most minimal, if any, ecological impact on the Americas.
Columbus also arrived after the later arrival of two waves of migration from Siberia, one of which brought the ancestors of the Na-Dene people during what was the Bronze Age in Europe, and the second of which brought the ancestors of the Inuits during the European Middle Ages, both of whom were mostly limited to the Arctic and sub-Arctic regions of North America, except for a Na-Dene migration to what is now the American Southwest around 1000 CE plus or minus (in part from pressure to move caused by the ancestors of the Inuit people). The Na-Dene ultimately heavily integrated themselves into the local population descended from the Founding population of the Americas. The Inuits admixed some, but much less, with the pre-existing population of the North American Arctic and largely replaced a population of "Paleo-Eskimos" who derived from the same wave of ancestors as the Na-Dene in the North American Arctic.
A few villages of Vikings settled for a generation or two in what is now Eastern Canada ca. 1000 CE before dying out or leaving (and leaving almost no genetic trace in people who continued to live in the Americas). And, the Polynesians (and perhaps others) probably made contact with the Pacific Coast of South America and Central America several times in the time frame (generously estimated) of ca. 3000 BCE to 1500 CE, again without a huge impact on the Americas or the rest of the world and with only slight amounts of admixture.
But the contact that Christopher Columbus made with the Americas persisted and profoundly changed both the Americas and the rest of the world. He returned to Europe and then came back with more Europeans who aimed to conquer the New World (including many covert Sephardic Jews seeking a more hospitable future than they had in Iberia).
Christopher Columbus's first contact led to a chain of events that resulted in the deaths of perhaps 90% of the indigenous population of the Americas (mostly due to the spread of European diseases like small pox and E. Coli, to which the people of the Americas had no immunity, at a time prior to the germ theory of disease, and only secondarily due to more concerted hostile actions taken by the European colonists towards the indigenous populations), led to the collapse of the Aztec and Inca civilizations at the hands of Spanish Conquistadors, brought syphilis to the Old World (especially Europe), brought horses to the Americas, led to the deforestation of much of North America, and brought crops native to the Americas including potatoes, maize, tomatoes, and hot chilis to the Old World (both Europe and Asia). Indirectly, this chain of events even led fairly directly to the Irish potato famine more than three centuries later.