Their capability to kill more does not imply that they would use it or there could not be systematic murder if they don’t use the full firepower. What I see is not just Hamas hiding among civilians (this is true and this is a war crime), but also what you conveniently ignore: systematic disregard of human life by Israel and ignorance of the duty to protect innocent lives. Some token actions to show for the press (all those „phone calls“) do not qualify as such.
What Israel should have done but did not: evacuate the entire population of Gaza to its own territory, ensure protection of human rights, guarantee access to food, healthcare and education.
Which legal term will be used to qualify Israel actions is less important than stopping this nightmare now and approaching the strategic goals differently.
If Israel wanted to systematically murder civilians there would be a lot more dead.
What you are seeing is the result of a terrorist organization hiding among civilians (human shields) while waging a war dressed as civilians (a war crime).