We will probably never know the actual source of the Covid-19 virus due to the cover-up and lack of transparency from the Chinese government. IMO the most likely source is a leak from the Wuhan lab (with probability around 70% IMO) and the second most likely source being the live market.
Let me state the conspiracy nonsense being pushed by the fringe that Wuhan was a military bio-weapons lab and the virus was deliberately leaked is pure nonsense.
Could be the virus was leaked from the lab via bat and the bat was eaten by a dog, and transferred to a fish monger.