Now that's not to say it couldn't have been engineered. There are certainly some possibilities (an unknown coronavirus being used as the basis for SARS-CoV-2 would probably be the most likely), but I don't think the evidence points that way at all. There's no reason to think it couldn't have occurred naturally, and genetic engineering is often very unpredictable (i.e. you don't necessarily know you're going to improve a virus' fitness with the changes you make), so the fact that it's so adept at infecting humans doesn't really point to it being engineered. If one were to make a coronavirus to infect humans for experiments, you would likely graft on a part of a known virus that you know is capable of doing that, which would almost surely be evident based on the genetic sequence.
So if it was from a lab leak, an accidental release of a natural virus that might occur when collecting samples, interacting with an infected animal, or attempting to isolate the virus would probably be the most plausible scenarios. But again, the different lineages that are seen in early infections makes the notion of a single escape somewhat less likely.
Ultimately, until there's a clearer source in nature, a lab leak can't be ruled out. But on a balance of probabilities, I don't think it's anywhere near the strongest possibility.
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