The lab-leak scenario presumes zoonotic jump, too. Just rather than from something in the wild, it's from humanized (ACE2-transgenic) mice, which WIV was known to be using to study SARS-like Coronaviruses.
The coronaviruses being studied at WIV included RaTG13, one of the closest relatives (96.1% genomic match) to SARS-CoV-2 ever found in the wild.
But a key difference between SARS-CoV-2 and it's wild relatives is the spike protein with affinity for the ACE2 receptor, so it would have had to have evolved through an intermediate host with a human-like ACE2 receptor. For example, ACE2-transgenic lab mice.
This does not itself rule out the wild-origin theory, but no wild host that could explain the missing link from RaTG13 to SARS-CoV-2 has yet been found.
Indeed. So the only reasonable conclusion so far is that we haven't found the reservoir host yet. This may take a while and it may even never happen. If and when we do we will finally be able to make another step in this whole saga.
> If there was GoF being done on the sample (adding of the spike protein to infect humans), that could be the remaining percentage.
I do not believe one bit the only "reasonable conclusion" is it has to be from nature.
Between the lab sample, the outbreak area, the GoF program being run, the timing, history of lab leaks, and the reaction, a lab leak is very reasonable...