I want a solution for Office 2010/2019 that restores the menus and toolbars of Office 2003 to the same place, and removes the "ribbon".

I've rejected Download Office Classic Menu for Office 2010 / 2013 / 2016 / 2019 / Office 365 (Word, Excel, PowerPoint) since it does not do the above. It just adds the old menu bar as a new menu. Likewise https://www.addintools.com/office201.../download.html.

Perhaps there's no such solution? If so, which of those that just add the old menus under a new menu would you recommend?

For Word, you can use the classic controls addin by Greg Maxey that you can download from here:
Ribbon Menu Control - Classic UI tab - by Greg Maxey
ribbon_menu_control_7[1].png
You can use Customize the Ribbon controls to hide the other tabs if you insist.

So, only that tab will show up. I would not recommend doing that though.
To find the link to download that file, search Greg's page for "Classic UI"

Thank you.

Or given that the ribbon has been an integral part of Office for over 20 years, you could even consider using it instead of trying to work around it.

__________________
Graham Mayor - MS MVP (Word) (2002-2019)
Visit my web site for more programming tips and ready made processes www.gmayor.com

I already did.

I decided to stick with the menus+toolbars that have been an integral part of my office for far longer.

I agree with Graham and expect that eventually you will find the Ribbon UI helpful. I totally rejected it in 2007 but eventually became comfortable with in with Word 2010. For a time, I used Greg's Add-In.
I eventually went down the rabbit hole of ribbon customization and love the power that is available.

That said, to each his own. Do, though, become cognizant of the contextual tabs that will show up when you are working with Headers/Footers, Tables, and Shapes.
These are extremely useful and quick ways to get to controls.

I'd need to survive to "eventually"

Thanks.

One more thought on "upgrading." You will have the option to update old .doc files to .docx, etc. While this is generally a good idea, I would advise doing it with copies because sometimes you can end up with surprising formatting changes.

.docx files are much more robust than .doc files.

Thanks.

I must have been lucky. I've not encountered any non-robustness with .DOCs.

What I meant is that .doc files more easily become corrupt and unusable than do .docx files. Also, with .docx files, which are essentially .zip files, you can unpack their components and possibly recover part such as the text or images from a corrupt file.

Thanks. Though I had that problem a lot with pics for the first 10yrs or so, since upgrading 25yrs ago, not at all, thankfully.

Nice to know. Thanks.

Right now, compatibility is the higher priority.