A lot of this is bordering on hand wave-y.

Bengal famine for example. Man-made, at least in it's severity, although the conditions that led to it were natural. Who is to blame? The British? Lots of people think so. And yet, British efforts to alleviate the famine fell woefully short because there was a war on, in that theatre with the Japanese and Siamese. Does the fault lie with the British or the Japanese? Who are you going to organize an international intervention against? Both warring sides? The Japanese wouldn't have allowed it, it was in their interest for Indians to be miserable. All that it besides the point that in that example, anyone who could help was busy with a giant war.

Digging down into the causes of the Bengal famine we see pretty stark evidence that, while natural and international conditions definitely were a part of the problem, they only led to an actual famine of that magnitude as a direct result of British policy in the region. Trying to say "well there were lots of reasons" is blatantly disregarding the acknowledged history of what happened and why.

Or, and we all know you were using this post as a guise to talk about this one, Gaza. Western countries are sending tons of food. By air, by land, and soon by sea. Israel is even sending food and working with everyone else who is. Do you know what's most notable to me? Who isn't. Iran, the weapons supplier who might have even encouraged kicking this whole thing off. Hamas itself, the government of Gaza, whose leadership remains safe in Qatar, while their people suffer from a war they started. Egypt, who has the only other land border. You talk about a legal obligation, but the only people who would listen are already the ones helping.

Israel is also stopping the majority of aid from entering Gaza and firing on people trying to retrieve dropped aid. Pretending like "so much" is being done is a slap in the face to the material fact that Israel is using starvation as a weapon.

Almost all of the food Gaza consumed pre war came through Israel. Quite literally biting the hand that feeds you, then parading around pretending it's Israel's fault.

Because it is. If you are going to be an occupier and deny the place you are occupying the ability to do things like produce or import vital resources, you now assume the responsibility of providing those resources and failing or refusing to do so means you are directly responsible for the harm caused by the lack of those resources.