What is the legal right of the Jewish people to the land of Israel?

Many advocates and Israelis mistakenly claim that our legal right to this land comes from the 1947 Partition Plan. But this is incorrect. The 1947 Partition Plan came through the UN General Assembly, whose resolutions are non-binding and can only make recommendations.

Consider this from another perspective: if the legal right of the Jewish people to this land came from the Partition Plan, it would mean that the Palestinians have a legal right not only to the West Bank and Gaza but also to parts of modern Israel. This is because Israel expanded its territories in the War of Independence after the Palestinians rejected the Partition Plan and started a war.
So, where does the legal right to this land come from?
The legal right comes from the Balfour Declaration, the San Remo Conference, the Mandate for Palestine, and the UN Charter. It’s ok, let me explain.
Balfour Declaration
The Balfour Declaration promised the Jewish people the establishment of a national home in Palestine, and the Mandate for Palestine, confirmed by the League of Nations, endorsed this promise.
What does “national home” mean?
National home in Palestine = Jewish state. How do I know? By listening to the British and Americans.
In 1921, a year before the Mandate for Palestine, Balfour and George Lloyd, then the British Prime Minister, told Chaim Weizmann (then President of the Zionist Organization) that the Balfour Declaration always intended a Jewish state eventually.
This understanding was shared by the Americans in 1919 also.
San Remo Conference
At the San Remo Conference, after World War I, the Ottoman Empire collapsed and was divided by the Allied powers. The conference decided on the distribution of the Ottoman territories, thus creating the mandates, including the Mandate for Palestine.
The borders of the Mandate for Palestine included modern Israel, Judea, Samaria, Gaza, and even Jordan, which was later separated from the mandate.
In any case, the San Remo conference established the mandate, which was responsible for fulfilling the Balfour Declaration.
The Mandate For Palestine
The Mandate for Palestine, approved in 1922, specified that its purpose was to establish a Jewish national home in Palestine.
Given that the Balfour Declaration intended a Jewish state, confirmed by the League of Nations in the Mandate for Palestine, and understanding the borders established at San Remo, how does this relate today?
In the War of Independence, Jordan illegally occupied Judea and Samaria. In the Six-Day War, after Jordan attacked Israel, Israel took back Judea and Samaria as an act of self-defense. Not to mention, Jordan renounced claims to Judea and Samaria (or the “West bank”) in 1988 and made peace with Israel in 1994.

What legal right do Palestinians have to ALL of Judea and Samaria that it can be called an occupied territory? Spoiler: None.
What is Israel’s legal right? This is where the UN Charter comes in.
The UN Charter
In 1945, after World War II, the UN was established. Its charter contains a crucial clause for the Jewish people. The powers decided to transition from the mandate system to a new system called “Trusteeship.”
Article 80 of Chapter 12 of the UN Charter ensures that the rights of peoples under the mandates remain valid. When the UN Charter came into effect, it included Article 80, which preserves the rights of peoples under all decisions from 1917 to 1946.
This article recognise the Jewish people’s rights to Israel, including Judea and Samaria. (Balfour Declaration, The Mandate For Palestine, San Remo Conference..)