For various reasons.

Different languages take different approaches and models to do stuff. Thus making each one better or worse for different challenges.

For example, python is easy and quick to get up and running. Bug it's slow and unsuited for low level programming (like OSes, drivers, and embedded stuff). On the other hand, C is very fast and very low level, allowing you to make both high performance programs and low level stuff, but it's a nightmare to use and you will run into all sorts of problems that an easier language, like python would avoid. All of this is mostly due to python being interpreted (instead of compiled) and c having manual memory management.

But they might also take a different approach at computation, like for functional languages (opposed to imperative languages) which try to solve problems in a more "mathematical" and declarative way, instead of defining a sequence of instructions. Or, even more, logic programming languages, in which you define a series of logical statements and the language tries to find solution and draw conclusions from them.

And some languages are designed around some particular concept that they think is beneficial and worth exploring, maybe taken from various other languages and put together, like rust which is designed around the RAII design pattern and takes large inspiration from functional languages, while still being and imperative procedural language (like C, so not object oriented). Or java which was designed to be a portanle but performante object oriented language, with support for low powered embedded system, full of features but simpler than c++, etc... all stuff that now is nothing special, but remember that java us very old. Or kotlin which tries to be java (they are interoperable), but modern and better and more "pure" or "consistent". Or c++ that started as an object oriented superset of c, but then started adding every single feature of every other imperative language, and never giving up on older stuff, to the point of becoming very hard to use correctly while making it very easy to screw yourself in the most intricate ways.

And of course there are domain specific languages (opposed to general purpose languages). Which aren't even necessarily Turing complete. They are designed for one purpose only, and they do that better than general purpose languages. For example AWK for text processing, or SQL for databases, or matlab for scientific calculations, or TeX for typesetting, or GLSL for shaders, or coq for theorem proving. And here imagination truly is the limit.

So, the point is, every language is more suited then other for some kind of work. And when people stumble across some problem that is hard to tackle and come up with some approach to solve it, or when they grow fed up with the issues of some older languages, they often like to make a new language around that. And some times this leads to entirely new paradigms which are worth exploring.

P.s.: I like languages:)