Did Columbus discover America even though Vikings reached it earlier?
Short answerNo; both are better understood as finding or rediscovering navigable Atlantic routes to an already inhabited land.
NotesNeither Columbus nor the Vikings discovered a land already inhabited by other peoples. Their historical significance lies in finding, proving, or rediscovering viable routes across the Atlantic. The comparison with lost industrial knowledge, including the modern difficulty of recreating 16-inch battleship guns, shows how societies can forget routes and technologies once known. Calling these voyagers navigators captures their durable achievement: they demonstrated that a route could be travelled and used again.