Let me save you the trouble. This story will likely end like.
1. They all die. Boo hoo.
2. They get scienced, transform or turn super saiyan and curb stomp the monster/ monsters later.
3. Army actually saves everyone towards the end.
4. God , disease or science kills them all.
5. Humans become the monster itself. And love it.
6. Time travel.
7. They go to a safe spot in the world hoping etc.
8. Magic, Psychics, they solve everything.
9. Philosophical post humanism no one gives a shit about.
There, the shitty horror manga checklist for Zombie, physical monster etc mangas.