Given the usual disclaimers that I barely speak for myself, let alone anyone else, that I'm not a member of the Debian and my opinion is worth precisely what an anonymous voice on a mailing list says...
The usual recommendations are to pick a standard OSI compliant license and not customise it. Using a standard license makes life easier for users because they don't have to think about the implications --- everyone already knows what BSD licenses, GPL licenses etc mean. My usual analogy is to suggest thinking about it like an API.
https://choosealicense.com/ is a good resource here and gives reasonable advice.
I'd suggest that if the author is concerned about people using their work commercially, then the author should look at the LGPL: this will make it easy to for users to use the library in another program, but will require that if the user modifies it or base work on it, they have to distribute the modified source.