Let's backtrack a bit.
First patient in France confirmed to be in late December 2019[0].
Retrospective wastewater analysis in Brazil shows the virus was present from November 2019 onwards, 3 months before their first reported case.[1]
Further down the line we have SARS-CoV-2's RdRP specific antibodies found during retrospective testing of samples of 111 (of 959) healthy volunteers of a lung cancer study in Italy[1]; samples taken in October 2019, meaning they got infected at least at some point in September 2019, 4-5 months before the first detected case. These antibodies also target RaTG13's RdRP, given that this protein is identical in both.
Even further down the line, and widely interpretable, we have the Barcelona case:
> "Coronavirus traces found in March 2019 sewage sample, Spanish study shows. The discovery of virus genome presence so early in Spain, if confirmed, would imply the disease may have appeared much earlier than the scientific community thought." [2]
The paper is here [3]. The fact that IP2/IP4 fragments of the RdRP gene are perfect match means that at least a virus very similar to SARS-CoV-2 (and RaTG13, its closest relative) was present in Spain back in March 2019.
It's not conclusive, as other markers tested negative, but it's also true that these other markers tend to degrade faster (for example, N1 marker wasn't detectable in May 25 2020, despite the pandemic ongoing). But this fact also rules out a case of sample contamination, because then N1 would have been detectable. It's also remarkable that the positive sample is from 2 weeks after the World Mobile Congress, leading to a self-contained outbreak hypothesis.
Now take all that information and combine it with the fact that no trace of SARS-CoV-2 has been found on any sample from Wuhan before December 1st, 2019.
While there's high probability that SARS-CoV-2 appeared within Chinese borders, mainly because the closest viral relatives have been known to live there (or Japan and South East Asia, if you ignore RaTG13), it's still highly speculative.
What is clear is that everything points in the direction of Wuhan, and the Huanan Seafood Market in particular, being just the first detected superspreading event, and the WIV was the reason why it was detected first, rather than the source of the virus itself.
[0] https://www.reuters.com/article/us-health-coronavirus-france...
[1] https://www.news-medical.net/news/20200701/SARS-CoV-2-circul...
[2] https://www.reuters.com/article/health-coronavirus-italy-tim...
[3] https://www.reuters.com/article/us-health-coronavirus-spain-...
[4] https://www.medrxiv.org/content/10.1101/2020.06.13.20129627v...