It was impossible to make all the same mistakes after the collapse, what was left of humanity moved far from the deserts and found the last slivers of green earth.
Learning to grow food was easy and intuitive, books survived and so then did knowledge, many buildings stayed standing, and held within secrets of the past.
Solar panels were warmed by the sun, turbines harnessed the wind, but oil, gas and coal had been depleted by the before people.
Deforested sands were soon seeded, succession gave way to the trees, and with new life poison was leeched from the sky, the after people breathed increasingly easy.
They rebuilt all that they could, and from the foundation of the past, they built a new future.