Once upon of time...
The Humans were the lords of this planet called Earth. Yet, they never valued the peace they had. They always tried new ways to gain an upper hand over the other nations. Ever since the time of the moon landing, they made questionable and cruel experiments...

One of those unethical experiments was merging human and animal DNA... an attempt to create a super soldier. However, it wasn't conducted only in one country... Independently of each other without the knowledge of anybody, the biggest three economies had that same wicked idea.
This way, three types of Beastmen were born. Their exterior look depended on the percentage of human DNA, as well, as their abilities on the animal DNA.

The first and strongest "Animal Man" was created from the ratio of 95% animal and 5% human. Bipedal animalistic creatures had all the animal resemblances except they walked upright on tiptoes.
Their fingers with claws looked like those of a raccoon to be of course useful. Their brain was driven by human intelligence which made some of them able to learn to speak human language and those mute ones were offered to learn sign language.
They were built to withstand lethal guns and harsh environments to be the ultimate secret weapon. Despite some of the human DNA, they were very cunning, temperamental, and hard to contain. They became too dangerous and were almost completely destroyed. Some survived and for a few decades got into hiding.

The second is the "Hybrid Man". A human torso and mind, but an animal head, paws sometimes hands/feet, and tail. The DNA ratio of 75% animal and 25% human. The power, abilities, and agility were insane.
Some were hairier than others, but all were able to speak clearly and had better control over their instincts and behavior. Emontionwise, those creatures were a little bit colder. Showing compassion and mercy was individual and sometimes questioned by them.
Should they even?

The last third one is the "Half-Blood" As the name suggests 50% animal and 50% human. They resembled closer a human being than an animal from the outside, but inside they were strong, agile creatures with superior senses. Very intelligent and adaptive to any situation.

All these creatures were used for the selfish desire to conquer the world. But what nobody expected happened... The Half human beings retaliated and turned on their masters creating a decade-long WORLD WAR.

The battles were bloody, cruel, and almost made the humankind go extinct. They tried everything and almost destroyed the planet to fight something they created themselves. At last, the remaining humans had to vacate their positions of the masters and hand it over to the new rulers... The Beastmen.

This way the new age of world peace began...