No. I've never argued Israel is not legitimate or legal. States come into being in many different ways. Israel is here, it exists, it has for some time now, it's legitimate as far as I am concerned and the world in 2016 is a different place than the world at the dissolution of the Ottoman Empire. The way I understand it, the Mandate was an agreement amongst the allied powers only to sort out the division of Palestine. No promises were made to any else.
This is Palestine.
It was created in 1920, so anybody born there is indiginous. Since Jews, Arabs, and Druze have been born there, they would be considered such.
Now, since Arabs cannot get along with anybody, it was necessary to divide the territory in such a way that the portion of the population they routinely persecute was to have a place to exercise their self-determination.
My question to you is this: If you claim to support such legitimacy, why does the entirety of your posting history on the subject consist of attacking it while championing the agenda of the Arabs who do?