Hamas barely has any power against Israel

Indeed. It would be nice if they would acknowledge the reality of their situation. Maybe they would release the hostages, lay down arms, and sue for peace, if they acknowledged as you do that they don't have any hope against winning against Israel with violence.

the children are not Hamas’s kids.

The children that they hide behind are Palestinian children. Hamas is the government of Gaza and every citizen there is under their jurisdiction and control until they are deposed; i.e., "theirs."

two wrongs don’t make a right

War is always ethically shitty, but I see no other option for Israel at this point. If they don't meet violence with violence and achieve meaningful objectives to keep themselves safe in response to Hamas' mass slaughter, it's just begging for more of the same in the future. War is what happens when deterrence fails, perhaps this will serve as an example to those who would consider attacking Israel next time of the consequences.

If you decide to shoot a innocent child you deserve go to hell there is no buts.

Israel's intention is not to shoot children being used as shields. It is to neutralize the one shooting from behind them, even if there's significant risk of hitting a human shield. This devalues the strategy and discourages such people from using human shields in the future. It's the same reason one does not negotiate for hostages, it encourages future hostage taking. You let this be a viable strategy that deters reprisal, expect more of it.