There never was and there is no “Palestinian” state. At most, it was the name given by the Romans to one of their provinces; never a state. On the other hand, Israel and Judah, to mention but only two, have been in existence since at least thousands of years ago.
About 3000 years ago, King David united them into the Kingdom of Israel and established Jerusalem as it’s capital. That happened 1500 years Muslim Arabs even existed let alone being “already there”.
No matter what, Israel was, is an will remain there, come what may.