Besides the above CDC quote, based on what I've read under normal circumstances the R0 of covid is roughly double that of the flu, the incubation period of covid can be up to 4x as long as the flu, the period of transmission is almost double, covid particles may remain in the air longer than the flu due to density and/or size, there are over the counter treatments for the flu which may shorten the period of illness/transmission and none for covid, etc..
In the 1918 pandemic people wore masks.. what's your point? Were the masks not effective? Did they also sanitize and social distance? Was there another illness circulating at the time that didn't drop off while they did this? Where were you going with that..?