The very first signs of human-to-human transmission in the epidemic were on Jan 14th, as some family members of the initially-identified cluster began to fall ill. At this time, there were about ~50 identified cases, and zero deaths.
On January 20th, one single incubation period later, as healthcare workers began falling ill, both China and the WHO confirmed human-to-human transmission.
There are large numbers of examples of respiratory illnesses that do not easily transmit between humans. Most commonly, there are frequently outbreaks of H1N1 influenza from farms, with animals as the primary vector. Among coronaviruses, MERS transmits very poorly between people.
Would you have preferred the WHO loudly proclaim the virus easily transmits between people when there was no evidence that it did? That would be absurd.
Please stop spreading this misinformation.