One argument against the cross-species transmission theory is that Chinese horseshoe bats (the reservoir for SARS and possibly SARS-CoV-2) don't really live in Wuhan. They live mainly in the south of China, see for example this map[1] from the paper "Bat Coronaviruses in China"[2]. This is where SARS was found in the wild, and where it first emerged as an epidemic[3].
It's not impossible that it would emerge in bats in Wuhan and spread to animals and then humans from there, just not very likely. Of course we know very little about the start of this pandemic so it's possible that an animal was infected in the south and transported to Wuhan, but that would mean that it happened without producing cases along the way.
[1] https://www.mdpi.com/viruses/viruses-11-00210/article_deploy...