Why can't you create files on your computer?

Question

ubuntu

Good evening, please tell me why it is impossible to create directories and files on the computer?
Writes that I do not have rights, but does not request them.
And why, when trying to go to Home, Desktop or other directories, does it show that there is no such directory?
For example, cd /etc will go to etc
cd /Desktop or /Home will not go, it can only go to /home, which is on the computer.
And how to copy path links to the directory where I am now?

Answer 1

https://en.wikipedia.org/wiki/Filesystem_Hierarchy...