I am just wondering why they couldn't use Namra to escape when she is half-bie state so she is not going to get bitten by zombie so she could just use herself to help the others.
They including herself didn't know what kind of state Namra is in. They never witness zombies ignoring Nam-ra like how they ignore Gwi-nam.
They didn't acknowledge the power Nam-ra had and how those power can actually easily save them from zombie. However, let be real here if Nam-ra just destroy the zombie like a superhero and easily save them from everything then the show will be bored.
Also, remember that we as a viewer has so much information than them like we know there is hambie that don't attract zombie, but they didn't know anything about it.
I do hope that there is the plot where they realize zombie will ignore Nam-ra and that she used herself to save the group in the last episode.
Also, they definitely missed Eunji vs Gwi-nam in the plot. Eunji become a hambie like Gwi-nam and I thought Eunji as the victim of bullies will do her revenge on Gwi-nam.