You are aware that a 'semite' is a "Jew, Arab, Assyrian, or Aramaean" - so, it refers to both sides in this struggle.
As to why "century after century after century" - largely religion, but that then shifts over into politics, and survival.
Do you think it's "anti-semitic" to disagree that a state should be created in an area by moving out the residents of that area to make room for them? Does not agreeing with Israel and their violence automatically make one an "anti-semitic"? Because it seems to me that the word, like 'vaccine', 'epidemic' (and even 'truth') has changed its meaning to suit a narrative.
The term 'genocide' now not only includes the actual killing of people, but also their forced displacement from their homes. To whom does that description best fit in more recent times? (And, we really *have* to look at more recent times, otherwise we don't have an end point to this... basically every culture has faced some form of 'genocide' throughout human history... but in 'recent' history, we have people who have lived through it - are still living through it)