@Macha I have never seen any of zorn's novel! But thankyou for the information and the green light to copy a premise, although I can't promise I will use it
If you don't mind reading a non-human MC there is I'm a Mom. MC become a zombie but she stayed sane because her child. It's not like she is OP but the enemy is weak because zombies.
The real threats are humans. Some humans are stronger than most because the zombie thing is an unintended side effects of creating super soldiers or something. Zombies are the failures.