Most of shared / reseller hosting providers that use cPanel as their control panel must have this order in their cPanel structure.
Example one Server with one IP address using cPanel
cPanel root / super user -> master reseller -> reseller -> shared
further down that many users / domains would use the ip
also cPanel shared hosting usually creates user directory under /home directory, so normally it will be hundreds of user directory right? but the screenshot says different, there is only one user directory
and when I up to directory above /home, there is no root directory
It is a little bit odd right? Yes and so it is called jailed SSH.
Basically, jailed ssh creates a shell scene within a particular directory where your shell activities locked in there. This intended to locked you into that directory instead of you being able to go freely to any other directories, something like ftp server does restrict you to your home directory. Also system administrator or host can decide or restrict what command or program can run in the jailed shell scene, usually they are disabling super user commands, so only basic shell command allowed to run in the jailed ssh.