This makes sense if the disease propagates linearly like bacteria on a petri dish. But it probably doesn't. It may spread more like a wildfire -- there can be burning branches blown miles from the main fire that only smolder or set a small patch of grass burning which flames out due to lack of fuel. Meanwhile the main fire is only stopped by water or other major geographic feature.

I could see it as possible. The spread is asymmetric. You could have one infected person who is not a super spreader only infect a few other people who just happen to be asymptomatic and not spread it to others. When your overall infected population is very small, like in the beginning of a jump from animals to humans, then you have a chance to get lucky in this way. Once you get to a larger infected population (like dozens of people) then you're more likely to have a super spreader and less likely to get lucky with only contacting asymptomatic people.

There are back-confirmed cases of covid in Italy in September 2019, so the Wuhan incident is definitely not a patient-0 situation (even if it could be a ground-0 location from previous patient-0 situation, but its just a guess and we'll never know).

Given that, having a case in Beijing in November 2019 is entirely plausible

Following that train of thought, what changed between Italy/Beijing and Wuhan? Was it sheer luck that made the first major outbreak happen in Wuhan, and not in Milan or Beijing? Or Los Angeles for that matter, I think I heard reports of suspect pneumonia cases from the US as well?

What I was alluding to with "precursor" was that it may have been the same virus, but that some mutation in Wuhan might have made it so much easier to spread. My mind just has trouble imagining a model where a virus can lie pretty much dormant for half a year in different populations, and then surge in one place only and spread from there. That may well be a limitation of my mind, I simply don't see how that would work.

If you have a deck with 2 hearts and 10 spades, your first flip could very well be a heart, even if with enough flips, 10/12 are spades.

What I mean by this is that viruses may have arbitrary behaviour when the infected population is small. Let's say as of September 2019, five people in the world were infected with COVID. It's actually not improbable or crazy that the epidemic outbreak only started in Dec/Jan.