We know with extremely high probability. It is genetically very close to bat coronaviruses. It is also not the first. Furthermore, a zoonotic coronavirus pandemic was already on the "Disease X" list, so it wasn't completely unexpected.

What we don't know yet is how it jumped from bats to humans. Is it direct? Is there an intermediate host? (pangolin?)

The more reasonable conspiracy theory is that the virus escaped from the Wuhan lab, possibly as a result of gain of function experiments. But originally, it is still bats, and what they could have done is not something nature is incapable of.