Considering how fucked up the whole tracing and research situation was once the scourge hit, (not to mention any proper experimentation on how to treat it, everyone was just trying anything because they were desperate) and how rapidly the variants have evolved once the scientists knew what they were looking for, I wonder if there might have been a less deadly variant or two earlier, which could have traveled out of China in apparently healthy people, while the deadly version was starting to wreak havoc in Wuhan. People who assume they have the flu often don't go to the doctor and get tested, since they'll just be told to go to bed and drink fluids. It was only when hospitals started to see a lot of very sick people testing negative for flu that they started to suspect something new.

But I'm not saying there definitely was.

Blood donation testing proves otherwise:

https://academic.oup.com/cid/article/72/12/e1004/6012472

Testing wasn't widely available until March 2020