Indeed there has been many tragedies in this world of ours. They each have their own unique aspects. The Nakba is incredibly unique because it was a massive war crime, initially backed by the whole world (via the UN) that has gone on for more than 90 years in full view of the public (i.e. 1920's onwards). BTW it is rather notable that of the list you provided, the US was responsible for most of the tragedies as indeed it is for the continuation of the Nakba (1960's onwards but prior via monetary and tech support). There's a lesson here as to who the 'goodies and baddies are' isn't there?
Abbas to urge UN to pressure Israel to permit entrance to Palestinian refugees from Syria (Haaretz)
from the article: Whatever you do, don't talk about the Palestinian Nakba!