Because serial ports (and modems) were pretty much the default thing to use (besides LocalTalk and AppleTalk) the desktop software usually supported that out of the box, no terminal required. This is also why Fax support was built in, because even then, any other type of peer connectivity wasn't really big enough. And around that same time, ClarisWorks was also really common on Macs.
Now, we don't know for sure that the author also had ClarisWorks, but we don't really know much about what was available in general (except the games, the sound files and the fax). But in general serial file transfers, modem and serial based methods were pretty 'normal' to have.
GlobalFax had a terminal emulator app included, most likely ZTerm, in this case.
from https://tagn.wordpress.com/2023/09/10/tech-support-at-the-vi...:
" the absolute garbage terminal emulator software we were including in the box.
And I set about pestering Rick to get somebody to Dave Alverson’s ZTerm terminal emulator app bundled with our modems because it was light and easy and supported the ZModem file transfer protocol which "
So the user could have likely run ZTerm to transfer the files.
Should we discover any more files to recover from the laptop, I may explore this avenue a bit further. If the ZTerm software is present, the trickiest part might be physically connecting the serial port to something else. Not an insurmountable problem.
I suspect you won't even have uudecode, in which case so long as you can transfer binary files, self-extracting ZIP files should work. Might take a while for larger transfers.
Getting a Real Operating System onto the old laptop would be a benefit. You might want to look into boot-from-floppy options including TomsRootBoot and Trinux. The former fits onto a single 1.5 MB floppy ("superformatted" to about 1.7 or 1.8 MB). The latter uses 2--3 disk images to include a number of more formidable tools.
Trinux still has a Sourceforge page, though I've not dug into it. You may need to hit up Internet Archive for working images:
<https://sourceforge.net/projects/trinux/>
A 2001 white-paper: <https://www.sans.org/white-papers/327/>
Tom's Root Boot ... seems to now be offline, but has a Wikipedia article:
<https://en.wikipedia.org/wiki/Tomsrtbt>
And numerous Wayback captures. The one from 2008 should be functional and suit your hardware:
<https://web.archive.org/web/20080724163531/www.toms.net/rb>
November 2023 appears to be the most recent active capture:
<https://web.archive.org/web/20231123003805/http://www.toms.n...>
And a ~2001 article describing TRB's capabilities: <https://www.linux.com/news/little-linux-distribution-could-t...>
The user should have consulted HN before diving into the problem. :)