Why are there so many programming languages?

Question

Nowadays, there are so many programming languages (C, C++, Python, Java, Hacks, JS libraries, Xhp, Kotlin....). I know that each one of them has its own purpose but why isn't there a way to unify efforts to make a default language for each field and maintain it. say for example C# for desktop. java for apps and so. This diversity is rather confusing. What should we learn and what should leave ?
;/ ?

Answer 1

So different things can be coded. Programming languages can do similar things but they all have their pros and cons

Answer 2

Different operating systems require different programming and in essence a different language to work with. IOS, Android, Windows, Linux all are operating systems that have their advantages and disadvantages and work better in different ways. To answer your question, you should learn programming/language for the operating system you feel more comfortable using and publish your creations.