How did they kill more than 4000 in less than a month?

Let me repeat - human shields. The blame is on Hamas. If Israel wanted to target and kill civilians it would have done in in a day. Hell, in half an hour.

they are shooting missiles at the towns they were expelled from in 1948 and 1967.

And jews where expelled from nearly all Arab states, (and from Europe by Nazis). So, it gives them right to target and bomb all civilians in all Arab states??

And it looks like you are okay with targeting civilians, as long as Hamas it is doing. And blaming Israel for targeting Hamas that uses human shields? The hypocrisy is astonishing. It is not even hypocrisy. The hypocrisy would have been if Israel actually were to target civilians (which it does not) and you where not okay with it while okay with what Hamas did the same. That would be hypocrisy. But since Israel not even targeting civilians, your position does not even have a word in a dictionary. (well, maybe antisemitism, but I will give you a benefit of a doubt and not going to call you that).

Palestinians have a right to resist a military occupation on their land.

Gaza was not occupied. And what Hamas did, shows that maybe they were wrong in leaving Gaza completely.

Look, I sympathize Palestinians, and I think that there should be two state solution at the end. But it just can not happen when there is Hamas in power whose declared goal is distraction of the neighbouring state and who is purposely targets and kills civilians. The tragedy of all that is that simple Palestinians become hostages of Hamas and dying as result of it.