There's nothing special about the name root, it's just a convention that it maps to uid 0. You can change it to something else and then rename an account with a

There's nothing special about the name root, it's just a convention that it maps to uid 0. You can change it to something else and then rename an account with a uid != 0 to root. Whether this breaks anything is largely distribution dependant. Whether or not that would result in the check being changed to see if "root" is uid 0 is another step in an arms race. Because with containerization or virtualization you can run as root with much more acceptable levels of risk than usual.