The Roman Emperor Hadrian re-named the region south of Syria from Judah / Israel to Palestine when he conquered the region in 135 CE.
The name change was an intentional act to dilute the identity of the People of Israel who Rome had conquered following the Jewish Revolt of 133-135 CE (AD).
Renaming a region was not unique to Palestine. Emperor Trajan renamed the region of the Dacians following their rebellion in 106 CE. From 106 CE and onwards the land and people of Dacia have been known as Romania and Romanians respectively. Not so with Palestine.
Hadrian chose the name Palestine, because that was a latinization of the name Philistine, the traditional enemies of the Jewish people in the Bible.
The heyday of the Philistine people was from about 12th Century BCE to 7th Century BCE when that people thrived in a confederacy of city-states: Gaza, Ashkelon, Ashdod, Ekron, and Gath.
As the empires of Babylonia, Persia, Greece and Rome conquered the region between 8th and 7th centuries BCE the Philistine people eventually assimilated and ceased to have a distinct identity in the region.
When Hadrian renamed the region Palestine in 135 CE, the ancient Philistines of the Bible and ancient history had not been a distinct people for more than 700 years.
In the following centuries the Roman Empire in this region eventually became the Christian Byzantine Empire until in 637/638 CE. In about 638 CE the region of Palestine was conquered by the Muslim Caliph Umar Ibn Al-Kattab.
I’m sure it will be surprising to modern eyes, but it was the Muslim Caliph Umar Ibn Al-Kattab who allowed the Jews to return to Jerusalem in 638 CE. When Hadrian quashed the Jewish rebellion in 135 CE he destroyed Jerusalem, renamed it Aelia Capitolina and forbade Jews to live there. Jews continued to live throughout Israel/Palestine, but they were forbidden from living in Jerusalem/Aelia Capitolina.
It was the Muslim ruler Omar Ibn Al-Kattab who permitted the Jews to return 500 years later in 638 CE.
Before 1948, all peoples of this region were referred to as Palestinians. Jews were called Palestinian Jews and Arabs were called Palestinian Arabs.
The zionist leaders who founded the modern Jewish State debated what that state would be called. There were suggestions to call it Zion or Hertzelia. Finally they decided on Israel. From then on Palestinian Jews were called Israelis and Arabs of the region called themselves Israeli Arabs or Palestinians.
In hindsight, it seems the zionists made a bad marketing move. Calling the Palestinian Jews Israelis left the name “Palestinian” available for the people who chose not to be called Israelis or Israeli Arabs. I think it also left of room for confusion about what it means to be Palestinian.
Historically, Palestine has never been a free land. By definition, the name Palestine was given by a foreign conquering army (Rome) to the territory it had conquered (Judah/Israel). From its destruction in 135 CE (and earlier) Palestine has always been ruled by a larger empire. Rome then Byzantinium until 638 CE. During the Islamic period it was ruled from Medina, Kufa (in Iraq), Damascus, (1,2 skip a few and then…) back to Byzantium/Istanbul and then London in 1917.
In truth, the region of Palestine as Palestine was never self-governed until the return of the Jewish state in 1948. Throughout its long history, the region known as Palestine has only been a free state when it was ruled by the Jewish Kings of @1000 BCE – 586 BCE and by the zionists of 1948 and onward. In between the region of Palestine was always ruled from afar.
I think it is good for Palestine to be free. I am happy that I get to enjoy that freedom. I am sorry that there are many in this region who truly are not free. I am sure that many of them will call themselves Palestinian. However, historically, it does not seem truthful to say they are any more Palestinian than they are Israeli, Ottoman, Byzantine, Turkish, Roman, or Greek.
There are many many people who are suffering in this region. However, Palestine is more free now than it has been in nearly 3,000 years.
My apologies for not doing a better job of offering sources for everything here. If there is something specific you’d like a citation for, please let me know and I’ll be happy to refer to you to a more authoritative source than me.