Personally, I don’t see a problem using ‘that’ instead of ‘who’. The fact is, so many people say it, that it’s become their truth. If you’re writing songs for yourself, your identity is a big part of what makes it unique. For example, if we we took that approach to grime/rap/urban music, a huge part of its personality would be lost.
Having said that, I do think that ‘who’ would flow better in your song, so...
I also agree that you could lose ‘that’ from the ‘you can’t face’ line. You barely emphasise it anyway, so would be no big loss.
I thought the song was great. What I’d refer to as a banger! As soon as the main riff started, I was nodding along. The vocals were very well executed (reminded me of James Hetfield). I also liked it when the riff cut out during certain drum fills and the solo. It gives the song that extra ‘kick’ when it returns.
Keep it up, man!