Why do you think that "surely" other Europeans reached the Americas before the Vikings? Someone had to be the first European in the Americas, and the Norse currently hold that title because of the amount of evidence conclusively demonstrating their arrival, while there is a substantial lack of unambiguous evidence in support any prior transaltantic encounters.

In previous posts, I've discussed a some of the popular candidates for pre-Nordic expeditions to Americas: the Welsh, the Israelites, the Minoans, and the Solutreans.