The first outbreak of the complete new virus was confirmed in the Wuhan Meat Market: a city in china, around the December. The first doctor to detect that there is going to be a pandemic is Li Wenliang
He informed chinese govt. without delay and called and emergency meeting to discuss this novel virus. In return the Police arrested him in the allegation of "spreading rumors", later in Feb 2020 LI took his last breath.
The honest answer is that we just don't know. We don't conclusively know the source.