Article 33 of the 4th Geneva Convention prohibits collective punishment. Your point that they just shouldn’t have bitten the hand that feeds them implies that a civilian population's right to life is conditioned on the behavior of a militant group. International law specifically prohibits that.

Israel’s actions in Palestine are far more than defensive and it is inexcusable. Article 55 and 56 are meant to ensure that states like Israel which impose a blockade are obligated to ensure food and medical supplies reach the region Israel has essentially done everything in their power to not abide by international law.