So, Christopher Columbus wasn't the first person to get to America. Regardless, he landed in American shores in 1492. The reason people say he discovered it is because he did discover it for Europe. For example say you found a new product. You would say you discovered it. You don't mean you're the first one to ever find it. You simply mean you've discovered it for yourself.
I guess the answer you are looking for is 1492, but Columbus actually didn't "discover" America he never set foot in North American. But he did land on various Carribbean Islands.
