A minor correction of a point you belabored, that there was zero sense of Palestinian Arab identity prior to 1947. Just that. Oh and that you kinda just framed this as an Arab-Jewish cultural war while conveniently ignoring, until it was pointed out, that this was primarily the result of White Western Christian issues with the Jews.
The Jewish homeland was a result of western colonialist promises and had its issues from the very beginning.
Any state though, being forcefully formed by planned immigration, based on religious beliefs, and backed by colonialist powers, it's bound to fuck things up in the area.
Yeah, it was a minor correction, because I don't see what you describe as having much to do with Palestinian identity. Those conferences would never have happened had there not been a Balfour declaration, and had the identity you describe been important, they would have accepted statehood when offered, or at least called for independence when under Arab rule.
One fact we haven't even discussed was that there was a large migration of Arabs into Palestine between the 1890's and the 1940's. Those people who met to discuss statehood, many of them probably weren't even born in Palestine, but rather came from other colonial territories, which the British would, a few years later, turn into countries. Places like Iraq, Syria, Jordan, and Lebanon.
Those Pals, even the ones who could trace their origins in Palestine back a long way, had about the same sense of national identity as the ones living in all those other colonial territories: not much. Traditionally, their identities were formed around tribe and locality first, broader Arab culture second, and the idea of nationhood, not so much.
Not until they were made into countries by the British after WWI as a reward for the Arabs helping them defeat the Turks during the war. Prior to that, and largely even today, there is one Arab culture, with one common language, one set of customs and traditions.
What the British did was take a large swath of land occupied by one people, and drew arbitrary lines on a map to separate them into different countries. yet the pan-Arabists were correct: there was one Arab people, one Arab culture. This has only barely changed today due to diverging experiences under different ruling regimes.
While those Pals who attended those conferences in 1919 may have rhetorically rejected pan-Arabism at the time in favor of a separate Palestinian state, they didn't say or do a darn thing about it for another 50 years.
So you'll pardon me for concluding that Palestinian nationalism, as anything separate and distinct from Arab nationalism, is essentially just a political tool for opposition to a Jewish state.