Do you have any evidence that Gaza's population is young because Israel is killing off the adult population? Just thinking about it, the numbers don't seem anywhere close to adding up. There's 2.3 million people, half of which are minors. To make that 1/3, Israel would have had to kill 1.1 million adults over the past generation.
My understanding of "Mowing the grass" is knocking out military and trade infrastructure, not genocide.
On the contrary, it looks like Gaza is so young because their population has doubled in the past 20 years. Gazans are just having shitloads of children. If my math and data are right, does this change your view on the reasonableness of using child soldiers?
I'm harping on it because I think reasonableness is the clear line around which we can assign blame. A group is generally not responsible for reasonable actions taken given their conditions. If you want to blame Hamas's tactics on Israel, I think you need to show that they are reasonable tactics.
Unless you can show me where 1 million Palestinians were killed/imprisoned/migrated over the past 20 years, I think it's pretty clear cut that half the population are children because the population just doubled.
Regarding male/female, the ratio you have is totally normal. Male babies are favored, but men lead wildly riskier lives and die younger than women.
I'm not seeing any evidence that Israel has meaningfully affected the population statistics of Gaza over the past generation.