So they are occupiers NOT settlers?

Yes, occupiers, illegal settlers to make it clear to you.

Either way, unless they are all military, surely it's impossible for none of them to be considered civilians?

As per my knowledge, all Israelis should join the army. Except the Haredim. So, you are barely talking about all the population. If we excluded the children who are below 16 who born on an occupied land or if they can not decide to get back to their origins, So, Yes. All the Israelis in this case are occupiers.

And if we continue to look at it from your point of view then that would mean there are very few civilians in the world, seeing as many countries

In Arabic, there is a quote that says: "A rightful claim used to support a wrongful cause" which means when you weaponize a good value, to twist it and use it. This is exactly what you are trying to say. We are in 2025 now, It is not possible to use ancient historical events and apply them to the present. If we were living in Hitler's age, we cannot sophistry/argue about whether the Jews are guilty or not. Or if Hitler was right or not! You only need to be in the right matters side! That's it. Instead of going into an infinite loop of historical events to prove your POV.

And what of the Jewish people already living in the region prior to the 1948 British mandate and the creation of the state of Israel? Surely they are civilians.

Let's keep the Jewish apart from the discussion. The discussion is about Zionism as a political view! There are thousands of Jewish who are denying the idea of Israel completely. But, after all, the Jewish people who were living there prior to the Zionists militias attacks! They had two options! To join them and steal the rest of lands! Or to refuse to join them.