one teenager dead.
One teenager died? Maybe he was a Hamas militant, and maybe not. Hamas does recruit teenagers... Actually, the US Marines recruit teenagers too. Teenager does not mean too young to fight.
And that is weighed against Hamas killing 767 civilians, including 36 children. They specifically targeted children for killing. They did everything they could to avoid engaging soldiers.
A good example is Shani Louk. She was a German tattoo artist in Israel for a music concert. She was taken captive brought back to Gaza, then raped repeatedly, then beheaded, and finally her body was dragged through Gaza. Even had Hamas mistaken her for a soldier, they would have known of their mistake during the days it took to kill her. And her being a captive meant there was no good reason to kill her.