world of hybrids

Centuries ago, when the world was dying from pollution, one of the scientists searching for a solution went mad, developing radical ideas. He genetically modified a plant so that it would consume everything in its path and return it to the earth. For example, oil—where did oil come from? From the ground. The plant absorbed it and returned it to the soil through its roots. It also broke down things like plastic with highly corrosive toxins. It also greatly aided the growth of vines and other fast-growing plants, like bamboo, growing incredibly quickly. Furthermore, it transformed carbon dioxide into oxygen with a toxic gas that was equivalent to smoking 100 cigarettes for humans, though it didn't affect animals as much. In a fit of madness, the scientist planted millions of these plants all over the world, spending all his savings and even taking out massive loans to continue producing and spreading them.
In less than a year, the plants had already invaded many cities. What the scientist didn't expect was that his body would begin to mutate, turning him into a rabbit hybrid. This was happening in many parts of the world; from an insignificant mouse to an imposing tiger, people were beginning to mutate, taking on animal traits and behaviors.
Little by little, the cities began to fill with these hybrids and plants that gradually swallowed the buildings, making them disappear. Politics began to dissolve until it vanished after the rebellion of many hybrids.
Centuries later, the world lived in a kind of harmony. With the help of scientists, they destroyed this plant and began to return to a less advanced technological era, quite similar to the 19th and 20th centuries. They began to rebuild buildings and small cities where "tribes" would start to form in each place. These tribes consisted of hybrids of the same species or breed, for example, felines with felines and canines with dogs.