The above photo is somewhat illustrative of the number of people involved in getting your book to market. Even if you self-publish there are still many functions that you may have not done yourself.
Below is not an exhaustive list but a rambling stream of consciousness when thinking about the people who are involved in the publishing process:
Author (kinda important)
literary agent (we think this is kinda important too)
contract department (legal)
proofreader (more than one?)
interior layout designer
copy writer (back cover and catalog)
printer (a full team involved at the printer)
chief financial officer
sales people (multiple in every publishing company)
special markets sales person
foreign rights manager
subsidiary rights manager (often the same person as above)
SEO manager (digital strategies)
metadata data entry (double check all the details)
online store coordinator (each “store” a different person)
brick & mortar store buyers
online or in-store merchandising manager
Add any that I missed in the comments below.
By the way, none of the above jobs are done for free. Thus the challenge of the economics of publishing.
If everything works well the group can create this picture: