They used the population of the Gazastrip as human shields, building there bases in the City sometimes near hospitals. Using human shields is a war crime.
Correction: Israel claims they used (and still use) human shields. Those claims have not been proven in any way. You'll say they build their military bases and headquarters in cities, but literally every military in the world does that.
Hamas doesn't want a two state solution,
Look up the 2008 and 2012 ceasefires. Hamas isn't fundamentally opposed to a two-state solution. It's not their preferred result, but they've taken part in serious peace deals more than once only for Israel to destroy the whole thing.
The Nakba was really bad and heavily shapes modern Palestinian consciousness, but nobody is seeking revenge for the Nakba itself anymore. It's more about retaliating against much more recent and current offenses, mainly the Gaza blockade and settlements, resisting Israeli occupation and freeing Palestinian detainees.