Wet markets were identified as the source for the SARS outbreak in 2002. Those were in southern China.
It make sense that the Wuhan virus came from the wet markets.
That is not to discount any contribution by the someone from the laboratory carrying another virus on their person.
But if you learn about these wet markets, the more you realize we will have an outbreak every 10-20 years from them.
I am no expert in this, but I do know that the SARS-COV-2 virus was isolated and identified rather rapidly in US labs as soon as the first infected were returned to this country.
I expect the Chinese would be capable of such with any sick people in that lab in Wuhan, whatever the source.
I am not a believer in “Jurassic Park” Lego virus building, but I certainly think a virus can be studied and grown in a lab. It could possibly be selectively bread for virulence and other characteristics, if not manipulated genetically.
The Chinese know the “wet market” and other “natural” sources of viruses are right there, next to their lab, too. I expect that that’s why the lab is there.