Cave-fish
Jack worked. He trimmed trees to keep the neighborhoods safe in the storms. Jack was useful.
The oil brought the storms. Storms took away the trees. Jack still had plenty of work with his neighbors. When the dust came, the farms went. Before the machines stopped, there was lots of fish for a couple of weeks. Nothing else, then nothing. There was fighting and leaving.
Now there is just dust and Jack. He stays in a cave north of the ruins. Deep in the cave there is less dust.
There were little white fish in the pools of the deep cave. Pale pink comes through the white shimmer if you bring them out into the light and dust. They had no eyes. Jack found out they didn't taste good. There aren't any more of them.
Jack took as much water as he could carry and headed north. He hoped he could find someone else. He wanted to be useful again.