There isn't really a single way to define a country. For background, I would recommend this video from the Map Men: https://www.youtube.com/watch?v=3nB688xBYdY

But following their conclusion: the thing that makes you a country is being recognized as one by other countries. Most of the world recognizes Palestine as a country (including 157 UN member states). Here is a map where the green countries recognize Palestine, and grey do not: https://upload.wikimedia.org/wikipedia/commons/0/08/Palestin...

What are the Palestinians then?

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.

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

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?

oh nice, you are making us all sob with those tough words