As far as I understand Israel doesn't claim that it didn't bomb a school area, it claims that it was filled with terrorists and had to go.
If I'm understanding this right, Israel is saying "this is the price that Gaza pays because we have to kill the terrorists" while also trying to minimize to the press how many civilians were actually caught up in these bombings.
Basically killing Hamas is above any Palestinian human rights for Israel, though I suspect that if the world wasn't watching, the genocidal government there would actually just straight up give orders to kill them all.