Don't delete  the home  dashboard but remove all web parts  (or inactive them
by unchecking them in the Content page) Add the document library web part to
the home dashboard

Tried that but am getting a script error when the
web part comes up: "Script Execution Error: Error executing INVOKE
query." It doesn't like the embedded content vbscript imported from
the standard document library web part.

Any ideas?

Actually, the document standard web part is not supported in the main
dashboard

What you need to do is

1. Export one of the standard web part like announcement, quick links or
news
2. Import it back on the main dashboard
3. Edit the setting, change the name
4. Change the title
5. In the part storage section, replace one of SPS defined Global variable
PORTAL_XXXX_FOLDER_PATH_HOLDER with the path you need for instance
/Documents "DAV:getlastmodified" DESC 5 to display up to 5 in descending
orders

In addition you will need to add some code to show Actions

I can email you a web part if you want.