OK, so everyone agrees that the Vikings/Norse/Scandinavians were first. Despite that, the impact of the Norwegians/Vikings, et al, discovery was negligible. I don’t really care about Columbus - he never made landfall in North America - and I’m not sure how savory a character he was, or exactly what country he was from, but, no matter - he certainly never set foot in North America.
Columbus reached South America on his 3rd voyage, and explored the Orinoco River among other places.
Voyages of Christopher Columbus - Wikipedia