Probably not helpful in this specific case but I identified as otherkin about 20 years ago as a young teenager. For me it was escapism from a hostile home environment but I did get over it after about a year. My friends eventually (correctly and mostly lovingly) mocked me for it.
Honestly I’m not sure but I don’t think it was particularly detrimental either. I’m glad that it reassured you! I was already pretty grounded in scientific thinking/materialism without knowing that’s what it was explicitly so I eventually just accepted it wasn’t real.