The information that they had was flawed and incomplete, which is enough to understand the degree to which they felt the need to sound the alarm.
The only people who are rabidly blaming the WHO for 'failing us' are the ones that would like to distract from the people the really failed us: the politicians that decided to ignore the information coming out of the WHO and that refused to act on it. Those governments that went a step further and played it safe did considerably better, but do note that those very same groups that are blaming the WHO are claiming that these countries only managed to do so by curbing people's freedoms, by abusing their population and so on.
On another note, the people who continuously talk about 'narratives' tend to be the ones that are most invested in sowing chaos and dissent as well as distrust in those authorities working hard to help us get out of this. The practical upshot of this is that you may succeed in undermining the sentiment that the WHO is a useful organization but that will not change the facts on the ground, and the isolationism that this is closely related to tends to be strongly associated with people who would like to reduce the world to little fiefdoms without such niceties as the UN, the WHO, the International Criminal Court etc. Be careful whose water you carry.
This is explicitly false. The WHO did not argue for strong countermeasures from “day #1”. They didn’t even acknowledge human to human transmission until late January 2020 (https://twitter.com/WHOWPRO/status/1219478547644813312?s=20 ). Here they are recommending against the general use of masks at the end of January 2020. (https://apps.who.int/iris/rest/bitstreams/1269003/retrieve). Here’s Tedros himself saying travel bans are not needed in February 2020 (https://www.reuters.com/article/us-china-health-who/who-chie...). The WHO only declared a pandemic in March 2020, apparently because they thought such a declaration would cause governments and individuals to give up (https://www.statnews.com/2020/03/11/who-declares-the-coronav...). All this after Taiwan initially warned the WHO in December 2019 (https://www.cdc.gov.tw/En/Bulletin/Detail/PAD-lbwDHeN_bLa-vi...).
The WHO absolutely did fail us and your claimed narrative is false.