Fact is: other explorers already had discovered America (they called it by other names in their own languages.) North America was reached by its first humans during the last glacial period, via crossing the Bering land bridge approximately 40,000 to 17,000 years ago.
Okay, then what about first Europeans to North America? These are said to have been Norse explorers around 900 a.d.
So, then, what did Columbus actually do? Fact is, he began by guessing that a ship could reach the East Indies by sailing west from Europe. The earth is round, right? He just wanted to cut the cost of importing products from the East Indies by sailing west rather than east.
So, Columbus set out from Portugal and discover parts of Central and North America and Caribbean islands. He lived and apparently died with the opinion that a ship could circumvent the American land mass and reach the East Indies. That remained his dream, his commercial goal: a cheaper, faster way of getting goods back to Europe from the East Indies.