Depends on your definition of "discovery". Christopher Columbus's trip to America changed the course of history. Any previous visits by the lost at sea sailors are not important.
History is always written from a perspective. If native Americans discovered Europe then whomever did so would have been recorded in their history. They would not go “ah but the Europeans where already there so let’s forget about this feat”
- as the first people to ever see it (their aboriginal folks)
- Discover to the world by the Spaniard crew captained by Columbus/financed by the spanish monarchs.
Everything else is just trying to mess with history, and if even any contact was there stablished they even didn't know for sure what american land was, even Spain wasn't totally sure if it was an extension of Asia or something of its own until one of its cartographers, the italian Américo Vespucio, determined it must be a continent of its own.