Edit: Sorry I quoted the wrong comment above. I meant to quote WhatsTheUseOfWorrying comment:
This is the crux of it. In its very creation Israel is viewed by some as an illegitimate state. It cannot, in their eyes, live by the founding UN resolution, which immediately prompted threats of attack from the Arab world. Attacks on Israel have happened ever since.
When discussing the Palestine/Israel conflict I often see people raise the point you have made that when in May 1948 the British moved out and Israel declared independence, the surrounding Arab countries and Palestinians themselves went to war against Israel. This is true but it doesn’t give the full picture. After the UN in November 1947 proposed partitioning the area into an Arab and Jewish state the Zionist leadership accepted the UN partition plan although they hoped somehow to expand the borders allotted to the Jewish state. They saw the UN vote on partition as legitimising on the international stage the idea of a Jewish state which had been their dream for the last 70 years. They also knew the Arabs would decline it and ultimately the borders would be decided in a war. The Palestinian Arabs (majority Muslim and some Christian) which were still two thirds of the population by 1947 - and majority owners of the land - and the surrounding Arab states rejected the UN plan and regarded the UN General Assembly vote as an international betrayal.
So after the November 1947 UN partition vote violence and skirmishes flared up again between the Jewish and Arab population. By May 15, 1948, when the British left and Israel declared independence nearly half (300,000) of the total number (750,000) of Palestinian refugees by the end of the Arab-Israeli war had already been forcefully expelled from the land by the Jewish militia. The surrounding Arab countries did as you say go to war with Israel on May 15 1948. What is often omitted is according to Israeli historian, Ilan Pappe, the Arab states sent troops into Palestine not as a reaction to the declaration of the founding of the state of Israel, but in response to Zionist operations that had already begun in February 1948, and in particular in the wake of the well-publicised massacre in the village of Der Yassin near Jerusalem.
The Arab countries help though was not straightforward as although part of them wanted to help they didn’t want to get too involved. Also Jordan who had the strongest army out of all of them at that time were ambivalent as behind the scenes the Jewish leaders had suggested a deal to them that if they didn’t get too heavily involved Israel would give them 20% of the land. This meant although they did send their army their participation was limited. Again according to Ilan Pappe, the Arab states in reality only sent relatively a small contingent of troops - smaller compared to the Jewish forces, and were and far less well equipped or trained.
Returning to why the Arab population did not want partition, it should be remembered that after the First World War the League of Nations acknowledged the right of Middle Eastern countries to self-determination. And indeed surrounding Arab countries such as Egypt and Iraq in subsequent decades - Egypt 1922, Iraq 1932 - achieved this. In 1878 only 5% of the local population were Jewish in what is now roughly the area of Israel, Gaza and West Bank (plus a small bit that is now part of Lebanon). Also they had been a small percentage for centuries in the area. Waves of Jewish immigration began from 1882 onwards due to awful European Christian persecution - Europe bears a lot of responsibility for contributing to the situation by their persecution of their Jewish populations over the centuries culminating in the horrific holocaust - with Jewish immigration especially growing a lot in the 1930s. This grew the Jewish population to about 32% of the area by 1947. There was increased Arab immigration too between 1920 to 1947 but not as rapid and from a much higher base than the Jews being the majority population for centuries.
Ideally the Jewish, Muslim and Christian population would have together formed one independent state. This didn’t happen due to Zionism and the wish of the rapidly growing Jewish population to make the area into a Jewish state. Their wish is not surprising considering the terrible persecution they had suffered for so long. The problem though is Palestine was not a land without people. I can understand why the Arab population didn’t think it was fair to divide the land into two roughly equal areas and wanted to form one independent sovereign state free from British rule. Hindsight shows they probably would have been better to have accepted partition. Israel have always refused to discuss the return of the 750,000 Palestinian refugees ignoring the December 1948 UN resolution for the refugees to be allowed to return.
Israel is now an established nation of 76 years and as such I believe it has the right to exist and is clearly not going anywhere nor should it. Gaza and West Bank Palestinians are also not going anywhere and have the right to become citizens of a sovereign state with all the rights that come with that, be it part of Israel or a newly created second state. At the moment they live either under military occupation in the West Bank with few rights, semi citizens in East Jerusalem or under siege in Gaza - yes Hamas, a violent, extremist organisation who I do not support - contributes significantly to Gazan civilians horrendous situation but Israel’s huge reluctance over the decades to allow Palestinians to form their own separate state plays a significant part too. Netanyahu has even said he purposely allowed Hamas to receive funding from other countries as he believed by strengthening Hamas he kept Hamas in Gaza and Fatah in the West Bank at loggerheads weakening the chance for a two state solution which Netanyahu and Israelis who support him do not want for various reasons. Even during the 1990’s Oslo peace accords between Israel and PLO, Israel under Rabin were still building settlements in the West Bank.
I so wish that enough Gazans and Israelis get rid of Hamas and Netanyahu’s government and new leaders on both sides can rise up and focus again on creating peace for both Israelis and Palestinians. I will end with this quote:
“Jews and Arabs, Israelis and Palestinians have to see each other as fellow human beings entitled to equal respect, rights and protections”. – Ralph Seliger