Israel isn’t killing everyone, isn’t setting out to impose collective punishment as a deterrent to future attacks, and won’t kill near 2 million people.
Israel is carrying out a military mission to ensure it is safe. It is telling the innocent to leave and giving warning (very unlike your German example). If Hamas and the Palestinians ensure a lot of civilian deaths to bolster their argument of disproportionate response, that’s their fault, not Israel’s.
The problem is that it has always been the case that among the people being bombed, it is the country that drops the bomb that gets the blame. If you were Palestinian there is just barely above 0% chance you would blame Hamas. So another entire generation will grow up hating Israel.
Crazy thinks if enough are killed, the rest will give up forever. Maybe, though some countries have tried that without great success. Maybe, it worked for Russia in Chechnya. It hasn't worked in other places.
No one is tackling the central point. Every time a target is hit AND innocent's are killed, what do you (and I mean everyone) think the families of those Innocents think? Do you really think they believe "damn Hamas did this"? And that assumes Israel ALWAYS has perfect intel. That is very unlikely, we (the US) have certainly blown up wedding parties and other innocent gatherings by mistake.
It has always been the problem in guerilla warfare, killing of innocents as either accidents or collateral creates more guerrillas. Am I wrong about that? It has not been addressed. If that thesis is wrong, my concerns are wrong. We have crushed militaries and won where a government surrendered. But destroying German cities did not force Germany to surrender, her military death did. Japan's military was also totally crushed, the last bit by the Soviets.
As to collective punishment, Gaza as a whole has been blockaded since 2007. Isn't that collective punishment?
This is still not an argument that the line has been passed, but that there is a line. It seems many believe that if every Palestinian is killed, that is just the fate of war on a stubborn people. I am not sure world opinion will hold out for that.