The ending doesn't make sense. The whole movie was about the MC trying to save his boy, so I don't get the twist. I feel the twist is not a natural twist but a force just to portray "humanity" but the director forgot his character's rooted behaviour. Humans have the instinct to survive, that's what the characters portray from the start until nearly the end. So to change that just to show another side of humanity contradicts the characters' values.
The twist isn't all a story is all about. The twist should be natural and not forced.