There is this total fantasy that lockdown was a choice to sacrifice the old to protect the young. It shows a total misunderstanding of how viruses and society works.
If there had been no lockdown the Covid peak would have been shorter but much steeper (same area under curve). At the peak society would have shut, regardless. Too many teachers would have been sick to keep schools open and, in addition, oxygen would have run out, meaning that many more young people, including children, would have died.
I don’t think children’s mental health would have been better if they had witnessed their parents suffocating to death at home as there was no healthcare available at all, and them having to watch the bodies for days as there was no one to take them away.
Covid was awful and some of the response was wrong but, regardless of the response, it was always going to impact all of the population.