Yes it is complicated, humans migrated across the globe at the start of language creation. Conquests standardised languages (Romans, Chinese Emperors, and many more) and languages influence other languages. The reason the world does not adopt one single universal language is national pride. However there is a good arguement for an international second language that is new and neutral - designed by language experts to be "pure" based on biology, psychology and other factors. Let's call this new Language "lang". I would learn English in the UK but also study lang at school. A person in Japan would learn Japanese in Japan but also study lang at school. A person in Turkey would learn Turkish (and Arabic) but also study lang at school. This is an exciting idea - it means anyone can speak to anyone in the world without having to learn many, many languages. In the world today, I would have to learn to speak English, Mandarin, French, Arabic, Spanish, just to guarantee the ability to speak to the majority of the world - but not everyone. Sadly I don't think the UN or any other organisation would be able to agree on this idea. So for now we must just learn as many languages as we need or want and hope we can be well understood.

oh, and um most alphabets are from phonecian, like hebrew arabic latin greek. asian systems are from the chinese system, made to standerize government protocol. mongol script was invented. it's complicated my friend.

because langauge developed in humans after populations diverged, thus language famlies: the aryans in europe, india, and iran, the uralics in finland and hungary and japan and korea, see within these famlies populations are futher isolated and develop their own languages, the same way cities talk differently, because they talk to one another. french is an evolved form of latin, german of germanic origins. then engish is the combination... in simple english: people are isolated, they form different languages.