I've always considered both of these arguments preposterous.
Firstly, I would consider 'ownership' of a piece of land to really just mean living on it. The Palestinians didn't own the West Bank or the rest of Israel/Palestine in terms of UN recognition as a nation state but the Palestinians lived there. They worked there, they farmed there. The fact that there wasn't and isn't a UN recognised Palestinian state seems to have been used as an excuse to treat the millions of Palestinians on these territories as if they're not humans or don't exist. A lot of the countries in the Middle East and Africa didn't really have too much history in their current states either, they were drawn with pretty arbitrary borders.
The difference is of course that the Arabs moved in almost 1400 years ago, in a time when religious nutjobs of all flavours were busy expending huge numbers of men and resources trying to take the 'holy land' and not pillaging and looting your neighbour was seen as the exception, as opposed to today. This was a time, when, correct me if I'm wrong, the Romans had already dispersed the Jews far and wide anyway. Or, putting it another way, talk me through the mechanism of returning all colonialists from 1400 years ago and since to their 'homes' and talk me through the mechanism of doing the same for the past 70 years.
Ultimately, I'm just a little confused why you would even bring this up tbh, in a discussion that has nothing to do with it.
As for the Falklands, rightly or wrongly, they're not going anywhere. The Argentinians can bring to bear no pressure, whether military, financial or diplomatic which would convince us to give them up.