Some people feel like a failure because they compare their self to others. Each person is unique starting from the day we are conceived. Many people do not take that into consideration, that some babies in the womb have a nice peaceful, secure and nutritious environment while others may have their environment plagued by loud scary sounds, drugs, alcohol, and lack of the necessary vitamins to produce optimal health. These are the extreme differences, but what about just the genetic differences of having different parents, grandparents, great grandparents, all of whom contributed to your DNA helping you be the person that you are. It can effect your temperament, intelligence, physical abilities, possible addictions you may be susceptible to (such as alcoholism) your facial features, your height , musical talent, artistic talent and so many other things about you. Even in the same family, siblings are not carbon copies of each other, in less they are identical twins, but even in that case, although identical looking and having similar likes and dislikes, identical twins still have a mind of their own.
You can only feel like a failure if you expect to have talents and personal qualities that are not compatible to your DNA, social or cultural exposure and have no ability to learn them and overcome the obstacles that you feel hold you back from what you want to be successful in.
There are many people who have overcome by perseverance and a desire to be more and do more. Abraham Lincoln was one of those people, Albert Einstein was another. Neither compared themselves to other people, they succeeded in their uniqueness. Would you consider Mother Teresa a success or Ghandi, neither wanted wealth or fame and both struggled materialistically knowing hunger, cold and other types of deprivation, yet they were successful in their achieving their goals. You can only feel like a failure if you define success on the terms of someone else's abilities, instead of your own.
We are not failures in this life, we are all students of our own circumstances and sometimes the things we learn and the success we have cannot be quantified in real world terms, but only in our hearts and minds.