The game wants to update from v. 1.01 (gog-3) to version 1.01 now in August 2020. Any info on this?

I don't know what has been modified, but the download size has increased considerably:
Changed download size - Installer, Mirror's Edge™, Windows, en - 6.3 GB ⇒ 8.6 GB (+2.3 GB)

I've checked this using the Wayback Machine. Korean and traditional Chinese languages have been added. The offline installer also offers Japanese language for the game now though not mentioned on the store page.

and the latest game update still won't work without Physx installed on my PC, even with it set to disabled in the .ini files.

I compared the previous Windows offline version (setup_mirrors_edge_2.0.0.3.exe) with the current version (setup_mirrors_edge_1.01_(40566).exe) and found the following main differences (some already mentioned):

- added new languages: LOC_CHS, LOC_CHT, LOC_JPN, LOC_KOR
- removed language setup (exe, ini, png)
- added maps with extension umap with the same file name as existing files with extension me1 (\TdGame\CookedPC\Maps for folders Menu, SP00 to SP09)
- added video file containing white asian characters on black screen (\TdGame\Movies\HealthWarning.bik)


All files including MirrorsEdge.exe in the folder \Binaries are identical (goggame-1893001152.dll got removed).

All files in the folder \TdGame\Config are identical


About the maps folder
I noticed the new maps with the extension umap not only have the same file name, but are also about the same size and in some cases also identical to the ones with the extension me1. I don't know if they were supposed to replace the me1 files with the umap files.

Example
\TdGame\CookedPC\Maps\SP00\TT_TutorialA01_p.me1, 2.809.798 Bytes
\TdGame\CookedPC\Maps\SP00\TT_TutorialA01_p.umap, 2.810.296 Bytes

The Maps folder in the new version 1.01 is about 7GB tall and umap and me1 files are each about 3.4 GB.
I deleted all me1 files and had also to delete the user config folder (%USERPROFILE%\EA Games\Mirror's Edge) to avoid an error message about corrupt config files.

A started a new game with the training course, Apart that the speech was gone (sounds were still were) I didn't notice any differences.

So there is now no way to change language without Galaxy?
Can somebody fiddle around and check deeper? (like for example if it reacts to ini files) Well there is this for confirmation:
https://www.gogdb.org/product/1893001152#changelog

Is there a way to download the original version?

There is a way. Use the Mirror's Edge Tweaks Tool.

Here are some great Tutorial and Tweak videos for the game:

Tutorials
Mirror's Edge Tweaks