The founders of the state of Israel were mainly people who settled in Palestine in the very beginning of the 20th century. They came mostly from Eastern Europe, inspired by romantic national ideologies rampant in their home countries, disappointed by their inability to assimilate into these new nationalist movements and excited by the prospects of modern-day colonialism.
Some were veterans of socialist movements hoping to fuse their romantic nationalism with socialist experiments in the new colonies. Palestine was not always their only option, but it turned into the preferred one when it became clear that it fits well with the strategies of the British Empire and the world view of powerful Christian Zionists on both sides of the Atlantic.
Since the Balfour Declaration of 1917 and throughout the British Mandate period of 1918-1948, European Zionists began to build the infrastructure for a future state with the help of the British Empire. We now know that these founders of the modern Jewish state were aware of the presence of a native population with its own aspirations and vision for the future of their homeland.
The solution to this "problem" - as far as the founding fathers of Zionism were concerned - was to de-Arabise Palestine to pave the way for the rise of the modern Jewish State. Whether socialist, nationalist, religious or secular, the Zionist leadership contemplated the depopulation of Palestine since the 1930s.
Close to the end of the British Mandate, it became clear to the Zionist leadership that what they imagined as a democratic state could only exist on the basis of an absolute Jewish presence in its territory.