Historically, Palestine has never been a country. The Romans captured Judea, and later expelled the Jews and renamed the province Syria Palaestina (after previous enemies of the Jews). After the Romans, many other empires held the land: the Arabs, Mamluks, Turks, British. But at no point was it a country. Even when the Egyptians and Jordanians captured Gaza and the West Bank, they didn't give independence to Palestine. Israel captured Gaza/West Bank. They gave full control to Gaza in 2005. So you could say Gaza is a country now.

Yes, that's the standard text, I know. (Just ignoring the arab movement since the 1880s to make it a country and the British promise to help with that).

But that wasn't my question. If Palestine isn't a country, then what are the Palestinians?

There are official old coins, newspapers, etc. with Palestine written on them. It has long been an entity.

Here’s a bit of history lesson: https://en.wikipedia.org/wiki/Mandatory_Palestine

TL;DR has nothing to do with Palestine of today