What can we reasonably say abouf the origin of the Covid19 virus?

I have heard contradicting stories about the first Covid19 virus entering the big world. From a chicken market to a lab from where it escaped. I even heard the story that pharmaceutical companies could have manufactured it by genetic engineering while the vaccine was already at hand. And I was surprised that a vaccine was found that quick indeed although Im not sure how long it takes normally.

How can we be sure which story is the right one?