This is by far an incomplete list, cause ultimately the full list will include what's in core-utils and many other packages. But the list you have, can easily be sumplemented with whats in available in
ls /bin and
ls /usr/bin (/usr/bin will be a long listing, so pipe it into
less). and start looking, reading and marking down.
/usr/sbin have commands that might be useful, but these are more for root than a regular user. There is never going to be a definitive list of commands to know "for development", because ultimately, each and every command has its place and usage, "for development" being way to ambiguous.
Also get a good unix book and read through that, that will take you through the more common commands also.
The os library and the shutil library are the best place to find these tools... in python. shutil having copy, copy2 and rmtree (The most used ones by me).