Those countries were ignorant with respect to how they viewed the natives of those lands. The U.S. has spent the last 200 years trying to right some of those wrongs with the Native Americans. It can't never be fully restituted to those people.
But that's just the thing, we're talking 17th, 18th, 19th century imperialism here. The World, unequivocally is a different place by the middle of the 20th century. Television emerging, paper presses and radio stations in every major city, cosmopolitan educators and improved and spreading universities.
There is no excuse of ignorance here, there is no excuse at all aside from the ridiculous divine argument.
I've got massive sympathy for the Native Americans, having some of their blood running through my veins and having seen first hand what those reservations are like. Knowing now what we know today, things would be handled differently. You can't say that in the mid 40's that perceptions of those people residing where Israel currently exists were all that different from what they are today.
To be fair, I'm not sure I fully understand your point, but this sounds to me like an awfully rosy vision of international human rights ca. the mid-20th century. In the US we have a situation where, frankly, the bulk of the indigenous population conveniently died/were killed off, so that by whenever exactly you wish to say 'more enlightened times' arrived, we no longer had an immense diplaced persons crisis (relative to our total population size) to deal with--which of course won't make surviving indigenous populations feel better about anything. Is this the 'progress' you seem to be alluding to here? Because as I mentioned upthread, there were millions of people permanently displaced not just by WWII but also its aftermath (the often-bloody final breakup of the 'colonial world'), and that was the mid-20th century too, was it not? The most devastating incidence of which, by far, took place not in the Middle East but in South Asia, where the 1947 partition of India (in which foreign powers were of course directly involved) permanently displaced at least 14½ million people and killed at least half a million. Granted, the states they resettled in were autonomous, I guess that's something; though most of them became new citizens of those states because they'd fled from massacres, not because they actually wanted to leave their homes. The Jews displaced to Israel and elsewhere by the Holocaust, pogroms, and persecution in Arab countries resulting from the 1948 war (about 800,000 Jews were displaced by the latter) would doubtless just as soon have not had those prompts to leave, either. None of which the Palestinians, who were also massively displaced (around 700-900,000 people), can be reasonably expected to give a rat's ass about, of course; I am merely making the point that sadly, there was nothing extraordinary for that time period in huge numbers of people being permanently displaced by territorial conflict.
I don't think you need a perception that indigenous peoples are literally subhuman to the point of being classified as 'fauna' to explain this sort of behavior; merely considering yourself culturally superior is enough, particularly if you perceive your own situation as desperate and are preoccupied with that. I think that in fact it would be surprising if most of the pre-1948 Jewish emigrants to Israel (not necessarily counting the small numbers who'd been there for centuries)
didn't hold such attitudes towards Arabs, since they were mostly emigrating from parts of the world (and under the auspices of a colonial power) whose majority inhabitants most definitely considered themselves superior to the Arabs--and pretty much all 'non-European' peoples for that matter, including Jews. Again, I don't understand why this should seem shocking; 'postcolonial thought' may have by now significantly transformed most of our perceptions of the colonial era, but that development quite literally took the remainder of the 20th century to transpire (the Cold War didn't help, as it provided a great motive to continue thinking of
colonized 'underdeveloped' peoples as a means to an end). Certainly that shift in thinking didn't magically kick in whole-cloth as former colonies attained independence, which had more to do with the major colonial powers being militarily overstretched than some great moral awakening, anyway. And sadly, there remain many places today where internal upheavals following independence continue to cause conflict.
Or am I not getting your meaning? Understand, I'm not trying to morally-equate anything into insignificance here; I am rather expressing surprise that anyone would think a land conflict whose foundations were very much laid within the colonial era, where one persecuted people's aspirations to statehood were put into contest with another's over their heads and against their will--leading, unsurprisingly, to repeated war--is somehow a shocking anomaly amidst all the bloodshed, displacement and border conflicts of the mid-20th century.