The Ottoman Empire’s historic tax records clearly show their Imperial dominion over a Levant province called Palestine for well over four centuries. L-o-n-g before Imperial British were able to opportunistically seize it in 1918, due to collapse of Imperial Ottoman’s at end of WW1.
As for the UN partition mandate’s specific terms of reference, this was 1947, and the particular semantics of the partition accord were merely reflective of those of the political driving force on the issue, Imperial Britain. Who in 1947 were colonialist by definition, and the Imperialist British institutions at the time were just as likely to have referred to a Mohammedan state, as an Arab, or Palestinian state.