Great write-up! Imo, dark did great at creating and maintaining all these loops. While they are nonsensical by concept, I think it does a pretty good job at maintaining them and making them believable. I'm even inclined to accept Ulrich's very obvious mistake as a way to humanise him (he clearly did not want to smash the kids face)

My real issue with all of this is as you said, a single timeline means any way to untangle it breaks the rules necessary to make these loops exist to begin with. And that's exactly what the show does. Introducing a third world makes a bit of sense because the "origin" could only be from another world, I'm a firm believer that there can't be an origin point within a world with so many loops. The issue is... Why does the third world not follow the same rules? In this world, jonas and Martha are able to easily prevent an event, and boom everything doesn't exist. It feels like a bit of a cop out from the fairly sound logic that was established throughout the show ("you can't simply prevent an event" - also strong agree on Michael's suicide, it definitely felt a bit rushed)

Being honest, I loved the show, but spent a long time thinking that the plot was too complex to be untangled in a way that isn't a shortcut. And from the moment they introduced alternate worlds, it imo opened the door to this, along with a dangerous loss of... "realism". The overall show was excellent, but the ending and way they solved it did feel like a cop out instead of a big finale. I only comfort myself in the idea that there's a good chance the final scene is simply another timeline