When those who have knowledge history talk about "Palestine" (or Fal-e-steen as known by the natives for hundreds and hundreds of years) they are not talking about a Palestinian nation state. For the vast majority of history, the concept of a nation/state did not exist.
Today the concept of the nation state is so ubiquitous that many have come to internalize the definition as natural and having "always been". This is not the case here. For example, the urge to imagine our collective ancestors as some sort of closed-off, well-defined, unchanging homogeneous group that has exclusive ownership over a territory that somehow corresponds to modern day borders has absolutely no basis in history.
Unfortunately, this is the foundational myth of many supremacist, ethno-nationalist ideologies such as Zionism and a fundamental mistake within the arguments of their apologists.
When nearly 3/4ths of your chosen holy book is routinely quoted by seemingly well-educated, ethnosupremacist psychopaths in order to justify genocide and the wholesale slaughter of innocents, then perhaps it's time to find a new holy book.