‘fictional character’
In Norse mythology, a valkyrie (/vælˈkɪəri, -ˈkaɪri, vɑːl-, ˈvælkəri/;[1] from Old Norse valkyrja "chooser of the slain") is one of a host of female figures who choose those who may die in battle and those who may live.
Going by your logic it would be acceptable to have an ‘American’ play a central role in a Australian Aboriginal Dreamtime film...
‘Highest grossing‘- completely irrelevant
I live in Sweden, am half Scandinavian and we all moved on from Norse mythology about a 1000 years ago.
But honestly, I'm a bit offended you would use my culture as a bat to whack others with.