Just like the world famous Maoz Tzur that everybody sings is originally a chri**ian hymn from the church! and lots of chasidishe nigunim were originally Russian or Polish marches and lots of Sefardi piyutim were originally composed by great Arabic composers (even for example by Umm Kulthum – an Egyptian anti semitic shikseh)and they were incorporated into the tefilah and sung even by great mekubalim!!
This is a very old issue and lots has been written about it. There is a ganse inyan (which time and patience doesn’t allow..) about being ‘mekadesh’ a nigun. Even from a tomei source!
Ahh so you’re gonna ask – so why do we go so mad when modern jewish singers convert a song by any of the modern goyim?? The answer is very simple. It all depends primarily on the type of song, who it was converted by, how it was converted, WHY was it converted etc etc. You need just a little bit of neshama to detect the difference between for example Shalom alechem and some of the new stuff by …I wont mention names…