The strange creatures were living in a place where there is plenty of nature and everybody was living happily. But, there came the construction of the buildings. It turned the rich, clean nature into a devastating place. At first, the creature tried to make and live, but the plant started to go rotten and the polluted environment started to give damage to the creature. That's when creature like a jellyfish saveed them and put them in a place where there is plenty of nature.
I think this was to tell us that if we keep polluting the Earth, we will have to abandon the Earth and go find a new planet to live in.