If evolution is fact?

The theory most linguists believe started languages is hominids made sounds for certain things (Watch out would be: Aahah!, etc.), and eventually they made so many sounds it became a language. How many different languages came to be could be that part of the group of people who speak that language could move. Say the language I made up started in the middle east. Some of the hominids moved to Africa, others to Middle Asia, Others to Europe, etc. Once the group separates, over time the language changes. (Like how instead of "They are here", most people would say "They're here".) This happens over a lot of time, which ends up being a new language.