How to rename files to numbers in Eshell?

[Felix E. Klee]

Consider a list of files:

    $ ls -1 *.jpg
    IMG_20210909_0003.jpg
    IMG_20210909_0004.jpg
    IMG_20210909_0005.jpg
    IMG_20210909_0006.jpg
    IMG_20210909_0007.jpg
    …

I want to rename these files to `1.jpg`, `2.jpg`, …, and I know how to
do it with Dired.  However, this time I want to do it with Eshell.

My own attempt, works, but I think there should be an easier way:

    $ listify *.jpg
    $ setq my-files $$
    $ setq my-numbers $(number-sequence 1 (length my-files))
    $ setq my-pairs $(mapcar* 'cons my-files my-numbers)
    $ for pair in $my-pairs { setq a (car pair); setq b (cdr pair);
      mv $a "$b".jpg }

PS: I already posted this on Emacs Stack Exchange
<https://emacs.stackexchange.com/q/68445/5327>.