That is but one of many reasons to oppose Hamas. Conflating their actions on Oct 7 (content warning: NSFL, cruelty, violence, death) with collateral damage caused while defending and retaliating against them is inappropriate, wrong, and in incredibly bad taste.
Your energy would be better spent objecting to those who provoked this war while using said children as human shields, hiding among civilians, and using otherwise protected areas as military assets. They are the ones subjecting children and civilians to danger and causing these deaths.
Israel has the right to defend itself even though collateral damage exists, and Hamas hiding among their own children does not make them immune from reprisals. If this strategy worked, we could expect more children and other civilians to be subjected to danger in the future as human shields.
My moral rules are applied consistently, I support our modern, western allies who care about civil liberties, and are defending themselves against genocidal opponents. I oppose genocidal belligerent Islamists who attack civilians. Not going to support for a group that would throw me off a building and opposes the enlightenment by forcing Israel to stop attacking them before they are deposed. Doing so is not a good deed.
The best way to keep civilians safe is to let Israel finish the job, because Hamas puts them at risk and is more than happy to kill them or let them die if it serves their geopolitical interests and makes Israel look bad.