Not sure I entirely buy the “it’s been everywhere for ages and suddenly just got switched on” angle.
What’s more likely, the magic sleeping worldwide virus, or, a bunch of folks actually had it following the real patient zero picking it up from bat/toad/dog, but either had a mild case, an asymptomatic case, or a serious case that was diagnosed as something else; then later, the wet market patient zero got identified with this new virus and presto, the bag was out of the cat.
Don’t get me wrong I don’t discount it being around for a long time, but the nature of exponential growth and all that, we’e still only detecting 10% of the cases, so it is entirely believable we had the same exponential growth for a long while before actually spotting it.