To be fair, Amerigo gets a pretty large tribute in the form of two continents being named after him.
But Columbus, despite his flaws, is still the first guy to take his ships west, hit land, and then return with good enough charts for subsequent explorers. The Vikings in Newfoundland is a fascinating story, and the mystery of Zheng He gives us some fun speculation, but neither triggered the massive changes in the Americas and Europe that came with Columbus's journey.