According to the Bible, the original inhabitants of the land of Canaan were the Canaanites, inclusive of several tribes. The original Canaanites were either destroyed by, or absorbed into the tribes of Israel; they are no longer identifiable.
The Jews occupied the land after the conquest that was led by Joshua; they maintained control of the land until the Babylonian conquest in 597 BC. Even at that time, many Jews were left in the land until the main body of Jews returned 70 years later. Since that time, the control of the land has changed hands 26 times; and Jerusalem has been leveled to the ground five times. (Documented in the book, “Why Christians Should Support Israel” by Dr. Mike Evans) During each of these administrative changes, Jews continued to occupy the land or else they returned in strength after each foreign administration changed.
According to Wikipedia, many Jews and Palestinians share genetic characteristics tying them to a common genetic heritage. However, Palestinians usually consider themselves to be of Arab extraction. The Canaanites were not Arabs.
Thus, the only remaining peoples who can claim earliest ownership to the land are the Jews.