Your statement is true and valid for the first few months of the pandemic, when everyone was frantically trying to get the infection rates down.

It didn't apply any more to the longer lasting second phase of the pandemic (that's the one I've been talking about).
Goal was to reach the endemic phase, meaning that almost everyone should get infected at least once, but without straining the healthcare system beyond its limits cause severe cases pile up in the intensive care units.

Kids had been known by then to:
a) not develop severe symptoms, thereby posing no problems for the hospitals themselves
b) being much less likely to infect other persons than grown-ups due to smaller lung volume and lower virus counts
c) be the most vulnerable group to lockdowns due to critical development stages happening in the early years in rapid succession

So the logical and responsible way to increase infection rates (which was wanted at that point to reach endemic stage) would be to keep schools and child centric activities open as early and much as possible, and only lifting restrictions for other groups of people gradually if numbers permit.

What happened instead is that restrictions were lifted globally for everyone based on incidence rates and hospital capacity (often divided by regions).
So, yes, school was open, but also the closed room restaurants and bars, where everyone was partying.
This rapidly let to shutdowns again to bring the incidence down (which took longer than the increase, due to involved infection maths).

So, for one and a half years the typical cycle was: Everything completely open for 2 weeks, followed by 3-4 weeks lockdown again, when the numbers had become to high.

In the analysis of the pandemic looking back, the handling of the school- and childcare situation has been the most criticized in my country, together with some nonsensical measures during lockdown (e.g. severe restriction of movement under open air).

So yes, children have been screwed unnecessary during the pandemic, mostly because some more influential lobby groups managed to push their agendas (e.g. hospitality industry and the influence of right-wing anti-vaxxer groups).