They are not all coronaviruses. About 12-20% of common colds are caused by a coronavirus. Most are caused by a rhinovirus. Influenza isn't even remotely related to coronaviruses. In terms of taxonomy, they don't even share the same phylum (Negarnaviricota for Influenza, Pisuviricota for SARS-CoV-2). Humans are more closely related to pigeons than SARS-CoV-2 is to Influenza.
Corhinovirus. Now, that would be a world ender...