Palestine was a peaceful part of the world while it was run by the Ottomans. That changed when Allied forces defeated the Ottomans and took control of Palestine. The British allowed Jewish refugees fleeing the horrors of Nazi Europe to overrun this area. The violence started when God's chosen people began committing horrendous atrocities in order to take what they claim God gave them (Palestinian homes, businesses, bank accounts, farmland, family portraits, ancestral gravesites...) by force.
Palestinians were forced to abandon their homes and properties by Jewish terrorist organizations. These terrorist organizations raped, tortured and murdered in order to terrorize innocent civilians and ethnically cleanse Palestine of non-Jews.
The ethnic cleansing and mass slaughters preceded the declaration of war by neighboring Arab countries.
Civilians who did not take part in the fighting were never allowed to return to their homes in violation of international law. Instead their homes were given to Jewish families as part of a systematic plan to cleanse Palestine of non-Jews which is also against international law.
Palestinians have suffered 60 years of oppression and injustice as a result of Israel's crimes against humanity. Israeli apologists can make up excuses to justify the unjustifiable and obscure this reality, but the root cause of this war is really very simple. People who suffer injustice and oppression, who have no hope for a better future, will fight, because they have nothing to loose except a life of misery and despair. Fighting is their only chance for a better future.
Over the last 60 years Palestinians have become angrier, better armed and more numerous. Israel has stagnated and is dependant on US aid to maintain a military advantage. This longterm trend will eventually lead to Israel's adversaries overwhelming israel's defenses and inevitably leads to Israel's destruction. That's my honest observation based on the facts and trends, not a wish. People who deny these realities do not contribute to peace, but contribute to continued Palestinian oppression and injustice and ultimately continued violence.