Also because this is an "alien" civilisation maybe they had projects (like the life extension one) to keep foodstuff/ clothing safe for something for 300 years or more and that is why that only the children in this town survived all this time.
Phase 1 of the project was to keep food supplies viable. Then when they ;learnt something from this project they started the life extending project from the same town.
As pointed out these urban kids with their non-existent work effort would have no chance of sorviving 300 years on canned food unless they teamed up with some farming group of pre-teens/
In realty the only people to survive this apocalypse would be aboriginal or islander kids who had been taught hunting with their parents off the land or sea. Even then they would be subject to accidents like broken legs or drowning etc,
Even farm kids would be subject to drought and flood and would have very little resources to manage it.
I doubt a group of adults would survive let alone children.
But thats not what Miri was about? It was supposed to be an allegory about chemical weapons.
As for cannibalism. I think it more likely that the kids would turn to farming than butchering one of their own. And why be a cannibal when you could kill a cow or sheep.
