- Balfour's declaration stated that the British government sees the creation of a national home for the Jews in favour.
- "...being clearly understood that nothing shall be done which may prejudice the civil and religious rights of existing non-Jewish communities in Palestine..." is talking about the arabs and christians living in Palestine, not "Palestinians", whose identity was created in 1964 by Yasser Arafat. Pre '48, "Palestinian" was used to classify the JEWS living in Palestine at the time, not the arabs.
- After WW2, Resolution 181, the partition plan was proposed. 45% (Judea and Samaria, Gaza, North Galilee) to the arabs, 55% (the coastal plains, the Negev desert, north-west galilee) to the Jews. The UN planned to make 2 states, not "1(a) jewish state".
- The surrounding arab countries (Lebanon, Iraq, Jordan, Syria, Egypt) threatened that if a Jewish state will be declared in Palestine, they will attack, invade and conquer it. The British mandate was coming to an end then as well, which pressured the temporary Jewish government to declare independence and as the arab countries promised, they declared war and attacked less than a day after the declaration of independence of Israel in 15 May 1948. That's when the war broke out.
- "imo balfour's..." As stated above, Balfour's declaration did not say anything about creating a nation (in your context I guess you mean a state? I might be wrong). It said that the British government sees the creation of a national home for the Jews in Palestine in favour, that's it. A very vague statement so that the British government wouldn't actually be committed to anything. Furthermore, it didn't say a word about the "Palestinians" but rather the communities and populations other than the Jews. (btw "...or the rights and political status enjoyed by Jews in any other country.")