Did you not read? its in the article you linked. No pathogen identified. Some of them may have had Rhinovirus too but obviously that was ruled out or they wouldn't have said "Despite extensive testing of multiple specimens, no specific pathogen was identified as the cause of the outbreak"

Again, if they tested the patients in July 2019 they would have noticed that the virus was very similar to SARS -CoV-1, if it were COVID. They didn't find anything though. The scientists belive it was the common cold and the scientists says that the amount of sick people was not unusual for that time of the year.

Why would closing schools have stopped a non communicable disease caused by a hobby? That is stupid. Furthermore Schools have been reopened for a long time.

Do you have a hard time reading? It says "the illness has not gone away". Also, smoking is something that's often done in groups, so it isn't unusual that it were to reduce if social activities stopped. Not sure why you are denying it, it did reduce the cases. I have much more trust in scientists that actually know stuff about this and have actually investigated it, than I do for random sceptics on the internet.

Maybe it was just not as deadly or communicable at that point? Covid mutates you know. If it were a precursor kids sharing vape pens it would make transmission far easier. If there is any chance this was covid why is there no investigation into the origins of covid in USA?

Yes but it ain't gonna mutate from a non virus to a virus. It makes no sense to investigate it further since there is absolutely no evidence that it's COVID. It's just wild speculation. If the only "evidence" you have is "but what if", then you should really reconsider.

Has anyone with any credibility suggested that the virus started outside China?

Why do they keep pushing for China to be investigated when it could have come from anywhere and just been identified first in China? M