Based on genetic analysis there is no doubt that an ancestor of the current SARS-CoV-2 strains originated in animals. What remains unknown is exactly how it crossed over to humans. The index patient hasn't been identified. Some sort of laboratory involvement seems unlikely, but we can't reject any hypothesis without definitive evidence.

Isn't it ususally that you proof hypothesis are correct instead of proofing them wrong?

This "I'm just asking, because it could theoretically be true" stuff is slowly getting tiresome.

No that is not at all how it usually works. The essence of the scientific method is formulating a hypothesis and then conducting experiments in an attempt to falsify it. The more experiments that have failed to falsify a hypothesis, the more confidence we can have in it.

https://en.wikipedia.org/wiki/Falsifiability

As a basic matter of epistemology we can almost never really prove a hypothesis. All we can do is agree that it fits the available data until something better comes along.

Until you found proof for a hypothesis to be correct. At witch point you usually stop trying to falsify that hypothesis. Applying that to the Wuhan lab theory, the correct way would be to properly falsify the natural jump from animals to humans first. Scientifically falsifying it. I have yet to see such proof.

EDIT: Of course these proofs have a certain likelihood of being false, hence all the p-value chasing and confidence-level adjusting.