Is there a module that creates a taxonomy of the world's languages?
I searched for such a module fairly extensively but was unable to find anything.

In the end, I used the Taxonomy CSV Import/export module, which allows you to create a list based on a CSV (comma-separated value) file, which is very easy to prepare.  I then referenced one of the lists of languages on Wikipedia.  I would share my list with you except that mine is specific to my site; it doesn't list all human languages, but instead just the most popular ones in Asia.