Hamas went into villages and murdered everyone they could find. They weren’t targeting military and some civilians being in the wrong place at the wrong time. They planned an attack to murder as many civilians as they could and executed that plan.
Before that for about a decade and a half they’ve been firing rockets towards population centers. It’s only because Israel spent billions of dollars to protect their civilian population that Hamas hasn’t been able to kill more civilians. And what do Hams spend their money on? Palaces in Qatar and tunnels under Gaza to keep themselves safe while they leave their civilian population at the mercy of an army they claim to be committing genocide.