If it was man-made, then there are three candidate scenarios. None of these ideas are mine. The first is that it was a biowarfare attack to stress test China's emergency resources and infrastructure in a novel way. This theory isn't very strong, because China's enemies have already gathered data on that from previous epidemic outbreaks.
The second is that this was surgically released by the Chinese on their own with the intent to let it spread worldwide. To what end, I don't know. Weaken the global economy to remind everybody how much they need China? No, that seems childish. This theory is even weaker.
The third alternative is that it was the globalists (Illuminati bankers, whatever you want to label it) and it's just another phase of their grand plan to weaken the sovereignty of nations and get another step closer to overtly controlling the world. This theory, while still unlikely, is the highest chance of these man-made scenarios.