This is one of those completely false things that people only believe is true by repetition. Go back and actually read the full set of WHO statements in mid-January. They have a bunch of statements saying there probably is person-to-person transmission, and a bunch saying that specific studies haven’t yet found hard evidence for person-to-person transmission (because at that point most of the cases they’d managed to find were tied to the market). The WHO never, ever said that it can’t be transmitted, and they absolutely never said that people should do nothing about COVID-19. They were urging nations to act for months before they actually did.