Interstellar world

Following the apocalypse's destruction of Earth, many people who gained special talents mutated into various animals. They managed to escape from Earth going into the galaxy, where they were detected by the galactic policy, which was likewise made up entirely of beastmen. Those beastmen, however, were not like the Earth's mutated. They were, in fact, the genuine pure blood. Earth's mutated beastmen became a member of their community with their assistance, and via marriages over time, there were no more pure blooded Earth's people in the cosmos. However, as time passed, the birth rate of the beastmen decreased, and only the lowest ranked mix blood people could give birth. (English is not my first language so I hope you understand if I make any mistakes. And please do give me your opinions toward my story.)