Edit1: Decide to change ‘by’ from Thin Lizzy to the The Dubliners.
As stated by @Semi-Hemi-Demigod@kbin.social, it’s not written by Thin Lizzy but in my view it was the inspiration to the Metallica cover. Even though The Dubliners are ‘credited’, it’s a old tradicional song.
Indeed it’s not, but according to wiki the Thin Lizzy version was ‘similar’ to Metallica one.