Do all children get all viral infections doing the rounds?
Mostly, probably, but we don't test them do we? And that's the difference with Covid. At present we are still doing "routine" testing. If we stopped LFT's many of those cases wouldn't be logged, nor indeed noticed, and the child possibly wouldn't even be aware they had the virus.
DD was run down/ill during lower sixth, as it affected her quite badly, she had a full panel of tests, privately, you don't get the full panel on the NHS. Turns out she had a number of markers for various viruses, but hadn't actualy been "ill" with any of them. She had, if you like, a form of long covid. Lasted a couple of months, but all was well. On the NHS, we wouldn't even have known what she had.
I only tell this tale, as it is indicative of you often only know what you have had, if you go looking for it.
We have to get away from testing and logging cases. Hospitalisations are key, as with flu. We have a vaccine, the population is something like 88% immune, it doesn't really get better than that.