I wanted something simpler — one consistent way to iterate over anything.

That's not actually simpler though. Simple is removing everything unnecessary. You took commands which could already do what you wanted, and added an extra program which calls them in specific ways. This will add bugs and maintenance headaches, not be portable, etc. This is added complexity.

The reason you made this script is not because you wanted simpler, you wanted easier. There's nothing wrong with that, and I'll grant you it probably is, especially for those unaccustomed to these commands. But easier != simpler. Often you'll find that simple is hard and easy is complexity deferred.