The author interviewed a lot of patients and doctors in Wuhan, and thinks the index case was a vendor at the seafood market, where live animals susceptible to the virus were being sold. She went symptomatic a few days before the accountant WHO identified did.
The problem is that she might have been the index case of Covid-19, but many SARS-COV2 infections are asymptomatic. So there could have been a lot of people who had infections but no symptoms before her! Or even symptomatic cases among hunters in Southern China or Laos who collected those animals and it either was never reported or not recognized by anybody until it got to Wuhan with their high-tech virology lab.
I think the best "virus origin" info is still the paper from the Pasteur Institute that showed all the SARS-COV2 RNA segments recombined from 15 other bat viruses.
We're flying electric helicopters on Mars yet you can't turn on your clothes dryer in Texas. That's because scientists are in charge of Mars, and Republicans are in charge of Texas.