Nothing is wrong with your system, you're just using the wrong path to `env`. The default location of the `env` binary is in `/usr/bin` and not `/bin`:

 $ type env
 env is /usr/bin/env
 

 So, your script is telling your system to use `/bin/env`, which doesn't exist, and that's why you're getting that error. Simply change to the right shebang and you should be fine:

 #!/usr/bin/env bash