As a fellow parent of young kids, I understand your perspective on this. My view differs. I'm not an anti-masker; I have worn masks whenever required, as have my kids. I'm not anti-vaccine; in fact earlier this week I just got my first shot, and my wife has been vaccinated for months. She got it earlier than me because of medical reasons. I did not, as I've posted here before, because of various factors (age, risk profile, health -- which is excellent, exercise -- regularly, no one I'm around on a regular basis with significant health conditions who cannot be vaccinated or would warrant me getting it, working remotely now a year-and-a-half, etc). I'm going to start traveling more and going into NYC more in the fall, and with that plus the Delta variant, I decided to get it. I don't know if it was the right call or not for my current situation, but that's where I landed.
For my young kids, I feel strongly there is more of a long term detriment to them having to wear masks every in school compared to the risk of them becoming seriously ill or god forbid dying from COVID. One of my kids has a speech-related issue, and having to wear that mask has absolutely impacted his development in that area. I think young kids learn more from interaction, facial expressions and the like, than they do from the curriculum at the elementary school level. I think "gaps" in the latter can ultimately be taught or addressed; I think the "gaps" related to the impact on the former is uncertain.
I've read multiple peer-review studies, thought-pieces or analyzes from credible sources which speculate that the long term harm for young kids wearing masks in school -- and what they have missed out or will miss out on -- may outweigh, in the aggregate, the potential health risk related to COVID. I've seen Catholic Schools and schools in other states go literally an entire year without masks and there not being a huge health issue for our young kids who did that. All of that gives me comfort. I also find it pointless, to some degree, because since last summer many kids in my area (Bergen County) who have had to wear masks in school all day are socializing and interacting outside of school without masks on -- with their friends and family, through town rec sports or travel teams, and the like. I don't understand why my 9-year old son has to wear a mask in school, but can spend all day at the town pool without one, or can spend the past year playing against other soccer teams from downstate NY and various towns in NJ without one, even though there is close personal interaction, unmaskless, associated with these activities.
I also don't understand why a school can't make mask wearing optional. Let parents who have a greater health concern, like you, have their kids wear masks. But allow me with my concerns to send mine without. The teachers, especially the older ones, all are likely vaccinated at this point or have that option, and so they are protected.