Based on my expertise from watching the movie Contagion, one possibility is that a sick bat flew out of the jungle into an open-air pigpen. The bat dropped a food scrap. A pig ate the scrap. A chef later handled the butchered pig. He shook hands with Gwyneth Paltrow during a kitchen tour. She then mingled with many people in the restaurant.

My original mental picture of the Wuhan market was that something weird was happening there, like people swallowing snakes live or doing a ritual with boar tongues. The movie scene demonstrated how a sequence of unremarkable steps could also do it.