If you want to use Apple’s system install of Python 2.7, be aware that it doesn’t quite follow the naming standards laid out in PEP 394.
In particular, it includes the optional symlinks with suffix 2.7 that you’re told not to rely on, and does not include the recommended symlinks with suffix 2 that you’re told you should rely on.
If you want to fix this, while sticking with Apple’s Python, you can create your own symlinks:
$ cd <somewhere writable and in your PATH>
$ ln -s /usr/bin/python python2
Or aliases in your bash config:
alias python2 python2.7
And you can do likewise for Apple’s 2to3, easy_install, etc. if you need them.
You shouldn’t try to put these symlinks into /usr/bin, and definitely don’t try to rename what’s already there, or to change the distutils setup to something more PEP-compliant. Those files are all part of the OS, and can be used by other parts of the OS, and your changes can be overwritten on even a minor update from 10.13.5 to 10.13.6 or something, so leave them alone and work around them as described above.
Alternatively, you could:
python2.7 instead of python2 on the command line and in your shbangs and so on. python, python3, python2, etc. don’t matter when you’re always using the activated environment’s local python.