It's a common trope for zombie movies to have someone sacrifice themselves for the rest to survive (ex. Train to busan), it shows how deeply they cared for each other.
Also, from a storytelling perspective it made sense that Caleb was the one that died. He did too many bad thing through out his life ( like killing unarmed survivors), so his death for his master was an atonement for the sins he had committed.
Not all stories need to have a happy ending to be satisfactory.
It's a common trope for zombie movies to have someone sacrifice themselves for the rest to survive (ex. Train to busan), it shows how deeply they cared for each other.
Also, from a storytelling perspective it made sense that Caleb was the one that died. He did too many bad thing through out his life ( like killing unarmed survivors), so his death for his master was an atonement for the sins he had committed.
Not all stories need to have a happy ending to be satisfactory.