Zionism can be both the nationalist movement for making Israel a Jewish state as well as the interpretation that such a movement is inherently colonial and racist.
So Zionism for Israelis might just mean "we support and advocate for a Jewish state in the land of Israel" which also includes two-state solutions but it can mean "we are a colonial and ethno-religious racist state" to the ones being displaced by the movement (like Palestinians).
78 years is not that far ago in terms of human generations, the children of the people displaced are still alive, and they've disputed it all the time since then.
Don't understand why you think 78 years is a long time, even less why you think it's equivalent to 1300 years.
The problem is that you assert 78 years is soon enough for the Palastinian claim to the land to still matter but 1300 years is too long for the Byzantine claim to still matter so we have a paradox of the heap situation where you have to choose a hard cutoff time period after which all claims to land are invalid.
So Zionism for Israelis might just mean "we support and advocate for a Jewish state in the land of Israel" which also includes two-state solutions but it can mean "we are a colonial and ethno-religious racist state" to the ones being displaced by the movement (like Palestinians).