If it wasn’t Columbus, it would have been the next guy.
And the next guy wasn’t that long after Columbus. In 1500, Pedro Cabral, salting to India was blown off course and discovered Brazil. If Columbus had never lived, the Europeans would have discovered the Americas. It was only a matter of time. The measles, smallpox, etc. would have decimated the Indians, who had been cut off from the rest of humanity and its diseases for thousands of years, in any case.