Wow, a lot of impressions here. Interesting.
Some of my impressions.
Somehow a running gag is that Rome and Paris are often described as traffic outlaw zones when Europeans talk about driving in Europe. I have only been to Paris and well ya, little bit unsorted on the large places and some opportunistic drivers - but OK.
In Germany I perceive a difference between the larger cities such as Frankfurt or Hamburg (more aggressive) and driving in the smaller cities such as Bamberg, Rendsburg, Wismar or Schwerin which seem like the country-side much more relaxed and patient. I did not mention Berlin because it seems to have a lot of traffic although the car density is by far the lowest in Germany. And of course the drivers from around Berlin needs to be counted on top.
In total Germany's North has less people than the South, so except the summer holidays the situation is more relaxed. Most often I use A24 and A14 which are very often free and widely unlimited. Traffic jams are a problem in Germany - especially in summer month and around the holidays people spend the most time in traffic jams (article with concrete numbers from 2024).
Of course we have drivers from our neighboring countries on German streets and most of them drive accurately, e. g. drivers from Poland, the Netherlands or Belgium. People from the Nordics often drive very relaxed but from there we have some Autobahn tourists who see our freeways as race track. This trend from 2000s / 2010s seems to be interrupted in the last years. The over-average technical quality of buses and trucks from Eastern Europe are still a problem which is now also moving more and more to Poland - their standards and checks improved significantly.
Since the speeding fines and checks were increased the numbers of violations feel going down. Ignoring red-light and other traffic rules is a real problem in cities, esp. with high ratios of e-scooters and bicycle users.
A final tip for travelers: this brochure of ADAC gives you an overview of German street signs in German language. I recommend DeepL for translation.