His voyage led to Spain becoming a super power and the first “global empire,” wherein Spain would hold assets in all hemispheres be they north, south, east, or west. Southern Italy, namely the kingdom of Naples, was already a vassal of Spain’s. Naples was a vassal to the kingdom of Aragon, which King Ferdinand ruled over. When he married Isabel to further the forging of a united “Hispania,” he brought his vassals to the union as assets. Once the conquests of New Spain began the Spanish Empire grew in wealth and power beyond anything that had been seen since the rise of the Western Roman Empire. Regardless, Columbus or Colón as he is known to us, was an agent of Spain and executed the will of the Spanish monarchy.

You’re technically correct, but given that Columbus sailed in 1492 and discovered islands in the Caribbean, he is generally given credit for discovering the “New World.” At least that was the story when I was kid some 30+ years ago. History gets revised and refined as new sources are uncovered and reconciled with the existing body of literature/evidence. Vespucci came after Columbus on subsequent voyages that aimed to understand the scope of Columbus’ discovery. I am not sure if anyone actually referred to the previously unknown (to 15-16th Century Europeans) lands as the Americas at the time, but it’s a modern convention aimed at making it simple to refer to the lands that would be uncovered as a result of his “discovery.”

Whether he was a “Gallego” or an “Italian” is irrelevant. His “discovery” of the Americas was a complete accident. He was trying to get to the “East Indies” and bumped into another whole continent by chance. Regardless, he did so with Spanish resources and Spanish crews, not Italian. He did so in the name of the Spanish crown. His “rediscovery” of the Americas (because the Vikings “discovered” it for Europeans first) was a Spanish accomplishment, not an Italian one.