This isn't about statistics. This is simple fact that Hamas has used children, including young children. It definitely uses 17yo and 16yo. If they used 9 (out of?) back then this simply means they don't care about using children in war.

There's things like making children lie in graves so they get accustomed to being martyrs, this is the longer story: https://aish.com/the-jihadist-who-converted-to-judaism/

I think it's important to understand this to know who Israel is dealing with.

On Israel's side of this I think it's clear Israel has been using fairly indiscriminate force at times. However even if Israel used has the most discriminate use of force a lot of children would get killed.

What do you propose Israel can do against Hamas? What would you do when 30,000 combatants are sitting on your border, embedded with civilians, in civilian clothing, want you to kill as many civilians as possible, use them as shield while launching attacks at you? Half of the population is younger than 18yo. What do you do when thousands of rockets are launched at you from densely populated places? Let's reset to Oct 8th, how do you wage this war?

Until you understand that for a very large number of Israelis Palestinians are sub-human you will waste your efforts trying to argue with Israelis based on rationality or ethics. They are racists full stop.

The reason is simple: it’s the combination of forced military and being the descendants of a generation that migrated and ethnically cleansed Palestine are overwhelmingly potent sources of indoctrination. Most people tend to assimilate and therefore they will blend into the Israeli military (and you see what kind of ethics they have) and most people find it difficult to condemn their parents and grandparents as genocidal monsters so instead they will favor whatever narrative absolves their lineage.