Why linux exist please ... so curious
Linux allows a user to control every aspect of the operating systems. As Linux is an open-source operating system, it allows a user to modify its source (even source code of applications) itself as per the user requirements. Linux allows the user to install only the desired software nothing else (no bloatware). For More Info: https://www.google.com/amp/www.linuxandubuntu.com/home/amp/10-reasons-why-linux-is-better-than-windows
You may gain more knowledge if you used your curiosity as an urge to search the net. That is if you are truely curious.
It was developed in 5 months by a 21 years old student as a free alternative to the commercial Unix https://wikipedia.org/wiki/History_of_Linux
It's the father of open source software. Git was first invented to manage Linux code and it was also invented by Linus.