First we see that Abraham actually did have more children than just Ishmael and Isaac. Isaac was still the heir of all the promises, but it is interesting to note that Abraham Abraham did end up with multiple sons.
Esau shows us the danger of impulsive decisions. He was hungry and to him food right now was more valuable than his birthright. The birthright came with a double share of inheritance and leadership over the family estate. Esau sold this for a bowl of stew. This is probably the most expensive meal ever purchased.
Jacob could have been a good brother and shared, but instead he saw his brother's weakness and took advantage of it. We too must be wise in our decisions. Impulsive decisions may have a short-term gain that has a long-term cost. People have gone into massive debt, quit good jobs/opportunities, and broken relationships due to a view of what I want today without consideration of long-term consequences. We are wise to consider- is what I want today worth the cost tomorrow? Of course, the number one consideration must be- does this decision honor God?