You are forgetting the Ottoman Empire, the Byzantine empire, the Roman Empire, the Ptolemaic Empire, the Babylonian Empire, the British Empire, the Canaanite Empire, and all the others I have neglected to mention.
That both are just random dates? That borders shifted continuously for thousands and thousands of years, and were called different things?
How do you arbitrarily pick a point in time, and say "Oh, this is the point land was stolen!". It's absurd. The same thing is true in every single country on the planet. There are people there, that took the land from other people!
I have some Scottish blood. The English took my land, 500 years ago. My ancestors were kicked to the curb, or killed in battle. Do I blame them? Or is that OK? What about the fact that the current English took land from the Romans? And endless waves of invaders between? Or war after war fought? Or the Romans from people before both?
Where does it end?
It's the same in every country on the planet!
Does all this mean that if Israel stands with static borders for .. what, 100 years, then no one can complain, ever, even once? Or is it 200 years? How long? What's the official time when the latest guy is the bad guy, but everyone else is pure and perfect?
The problem here is we're both unsure, but you're pointing at the UN. I'm throwing my hands up and saying, that no country on the planet can stand if the metric is "They took my land".
The time is generally 'reset' after a fairly long period of peace, but that doesn't prevent people declaring their own independence. You'll note Scotland had a referendum on this.
How long must Putin occupy parts of Eastern Ukraine until it's 'his'?
Throwing your hands up is just surrendering to the strongest power.
And if one is going to play the historical game, Jews have had statehood there for thousands of years, until it was stolen, yes?