Actually humans don't have lasting immunity to the 4 cold causing virusesIn your opinion.
C. 20% of "common colds" (you know them; the stuff you shuffle off every few weeks or months, complaining about "feeling like shoite" or some such) are coronaviruses.
We have herd immunity to them.
My bet is that, in months, years, or God forbid, decades, the 'rona will go the same way.