I’m really not understanding this or following this. If you like the melody you like the melody. Why do you have to know where it comes from? If you don’t like heavy metal, there is no way you are going to like it if it has Jewish lyrics to it. If you do, then there is something wrong with your taste in music and it has nothing to do with the fact it is a goyish nigun. If there is something wrong with heavy metal then it is improper for goyish and jewish music!
If you don’t like rap music then you don’t like it whether it is english goyish lyrics or english/hebrew Jewish lyrics. You either like rap music or you don’t. We are talking about the melody/nigun/music here. Music has no inyun of kosher. It is a melody, a series of notes. You either like it or not. It makes no difference if you can sing english words to it or hebrew words to it, if you like the nigun you hum it. If you are an American citizen you should know the words to the National Anthem and the nigun, there is no excuse for not knowing it. AND yes it is in english and goyish but it is the National Anthem of the country that gives you freedoms and the right to live here and enjoy them.
So again, what is the big hooplah? You have the right to choose the music you listen to and b”h there are many choices, there is rock, jazz, country, hip hop, chassidishe, modern, chazanish, children’s, classical, rap, pop, and more. Some help you exercise, some help you relax, some help keep you awake while driving, some inspire, some are just plain fun. Music is entertaining, please don’t make a religious issue out of it.