Why couldn't Palestine defend themselves from the Israeli terrorists?

The sheer destruction created by the Israeli army outrivals some of the worst atrocities in the Palestian-Israeli conflict, but this has gone too far. The numbers on the Palestian is well above into the 700s death toll, which has now evolved into an epic human crisis with food shortage, medical demands on a larger scale than before,etc. What infuriates me the most is that the Israeli officials do not have a basic human decency to stop all conflict. They knew that they were killing civilians, that much could be found certain from the piles of damning evidence against them, yet they continued killing more women and children they could afford for the short time given. If this is how a country defends it sovereignty then all countries must kill other groups to protect their legitimacy