Cabral in 1500, trying to sail around Africa to get to India, accidentally discovered Brazil--so if Columbus had never sailed, Europeans would have learned about the New World pretty soon anyway.
A couple of Genoese sailed west in 1291, I think it was, and were never heard from again--they could have been lost at sea, or perhaps reached America. Maybe they were eaten by Caribs.
The distance between Greenland and North America is about 200 miles. Not even a weekend fun sail for the Norse.
Most likely there were other earlier contacts with Europe.
“Sailors sail, that is who they are and what they do.”
Yes, I agree. I have read about evidence of runes being found in some unexpected places in NA.