I would be interested to be proved wrong but I’ve not been able to find this myself or by asking knowledgable people however the oldest properly documented actual record of a sale of property including details of negotiations and prices is the purchase of a cave in Hebron by Abraham for the burial of his wife.

Please find me an earlier detailed record of sale (not just statement that people owned land) because I too have trouble believing this is the first.

Certainly, for Jews, the story of coming out of slavery in Egypt is a huge part of our identity as moving from slavery to freedom. I also believe this concept came out of Judaism and into the west via Christianity.