And if chimps evolved from a common ancestor as humans then how come chimps never became as smar
To ask why chimps and humans are different eventhough they have a commom ancestor is akin to asking why spanish and italian are different languages eventhough they have a commom ancestor language (Latin)
After being separate, the two species found themselves in different enviroments and grew apart. Even more important then that is the fact that the evolution of a species depends on a sequence of random events that cannot be replicated by a second species. That`s the nature of historical facts. They happen once and cannot be replicated.