And this monkey ancestor is the same animal as our human ancestor.
If we trace our ancestry back to about 10 million years ago, the monkeys that existed then are not only the ancestors of humans, but also of chimpanzees, gorillas, and orangutans. From this common ancestor, the orangutan diverged, followed by the gorilla, and about 5 million years ago, the chimpanzee and human are thought to have diverged.
The separation of chimpanzees and humans does not mean that they were suddenly born separately. They were born in the same way as we see today, with gradual changes over thousands or tens of thousands of years. This is called evolution. Naturally, during that time, we evolved from chimpanzees and began to acquire human characteristics, and there must be a time when we can be called human. Of course, evolution occurs gradually, so there are no clear boundaries. The oldest known human is believed to be an animal that lived in East Africa about 4 million years ago. This animal, called "australopithecus afarensis," had unique characteristics not seen in chimpanzees, such as the fact that it stood up straight and walked on two legs. However, its brain size was about the same as that of a chimpanzee, which is considerably smaller than that of today's humans, indicating that it was still a monkey and in the process of evolution.
It is thought that during the 4 million years that the Afzel ape man has been passing on his descendants to the next generation, his body has gradually changed, and we have come to be what we are today.