Even though Abraham was old as fuck he got married again. Or maybe he’d had this third wife all along, but this was the first time she warranted a mention. Anyway he had a bunch of other kids besides Isaac and Ishmael, but only those two really count, well, really only Isaac counted. When Abraham died, Isaac inherited everything sans gifts for all his siblings. Ishmael came back for the funeral and they buried Abraham in the cave with Sarah.
All of Abraham’s kids had a lot of kids, but again, the only ones that count are those of Isaac.
It took Rebekah a long time to get pregnant, and when she did, it was a really rough pregnancy because she was pregnant with twins. The firstborn twin they named Esau, and he was really hairy. The second twin was named Jacob. Esau grew up to be a hunter, but Jacob was a homebody. Isaac preferred Esau because he really liked the taste of game meat, and Esau was a great cook. However, Rebekah preferred Jacob. One day, Esau came back from hunting totally famished. Jacob happened to be cooking lentil stew and Esau was all, hey bro, give me some of that stew! It smells delish. Jacob was a bit of a dick and wouldn’t give him any, so Esau was like, bro, I’m dying here! Give me some stew! I’ll give you whatever you want. So Jacob was, I’ll give me some stew if you give me your birthright of primogeniture. Esau was like, whatever, it’s yours, just give me some stew.