God who created the universe is the owner of all the earth. God said in His word: “… for all the earth is Mine… These are the words which you shall speak to the children of Israel.” (Exodus 19:5-7 RSV) and He gives it to whomever He desires and plans. He said to Abram while…“the Canaanites were in the land (doesn’t mean they owned it) ‘To your descendants I will give this land.'” (Genesis 12:6-7 RSV) and according to His word, the Land of Israel belongs to Him.
Abraham had a son, Ishmael from his wife’s Sarah’s Egyptian maid, Hagar, but God said he was not the son of promise. The seed of promise was Isaac who was later born to Abraham from Sarah, a miracle from God, as He has promised. That is why He gave the promise of the Land also to Isaac. He told Abraham to let Ishmael go out of the land to another place and that He will make him too into a great nation. But God said to Abraham, “… for through Isaac shall your descendants be named.” (Genesis 21:12-13 RSV) So God repeated the promise to Isaac (not to Ishmael) “… …”to you (Isaac) and your descendants I will give all these lands and will confirm the oath I swore to your father Abraham… so that you may take possession of the land where you now live as an alien, the land God gave to Abraham.” [Genesis 28:4]
God repeated the promise to only one of Isaac’s sons, Jacob who’s name God later changed to Israel. That is why He calls Himself the God of Abraham, Isaac and Jacob – The God of Israel. God said, “I am the God of your father, the God of Abraham, the God of Isaac, and the God of Jacob.” (Exodus 3:6 RSV). According to God’s promise and plan, the children of Israel (God delivered from slavery in Egypt) came into the Land and possessed it under Joshua’s leadership.