Much of the records of the Viking Era were written by their enemies.
The early Vikings were raiders that plundered the cities, and towns of England and Northern Europe. The Norsemen were feared and hated.
The people writing about the Vikings did not understand the culture, religion or language of the Scandinavian people.
One of the things that their enemies did not understand that the term Viking was a term used when the Norse were raiding, it was not an ethic term. Most of the time the Norse were traders and farmers. The Danes conquered much of England and stayed. The Norse settled and became part of England.
The Viking warriors did not wear helmets with horns. The Catholic priests whose Monasteries , Churches, and abbey's were plundered by the Vikings called them devils. The writing of the monks depicting the Vikings as evil pictured them with horns.
The Norse converted to Christianity adapted to the culture of where they settled. The Norman kings of England were descendants of the "Vikings".