N=1 and highly subjective of course, but I don't remember A) our kids falling ill with random fevers so often, pre-pandemic and B) my wife and me being infected by them in turn so easily
“It varies a lot among kids. But most babies, toddlers and preschoolers can have as many as 12 colds a year and still be normal. On average, you’ll probably see between seven and eight infections a year. This number may be higher for children who are in child care or when they start school. It’s also typical for kids to have symptoms lasting up to 14 days. And sometimes a cough can last up to six weeks. That means kids can be sick for a majority of the year and still have a pretty typical immune system.” https://mcpress.mayoclinic.org/parenting/the-constant-cold-w...
That being said, I do remember that the first cold season after people started going out again being nastier than normal.