And of course you will eventually get infected by an additional cold, because there remain more than 300 different runny nose viruses. Yet you will never acquire the same runny nose infection that you had before because you have established immunity to it.

Parents have in the past had a great deal of the runny nose viruses. Grownups have created resistance to the colds they have actually had. Therefore there are not lots of runny nose infections around for adults to become infected with. That is why parents only succumb to a couple of colds each year whereas children acquire 10-12 colds each year.
https://emilianoteqs.bloggersdelight.dk/2022/01/09/natural-treatment-for-hpv-and-cervical-dysplasia/