Here, in the Western world, mainstream religion does not often believe in reincarnation, instead, they believe in essentially that there is only one life, and therefore when this physical life is over, long or short, good or bad, fair or not, that this is all that there is, on this physical plane. There are many reasons to believe that this belief is flawed, even tellingly from passages in Scripture, such as "But I say to you that Elijah has come already, and they did not know him but did to him whatever they wished…" (Matthew 17:12). So too, even a cursory glance at the world at large, demonstrates the reality of the circle of life which is all around us; an endless cycle of birth, death, and re-birth, again and again and again.
For those that do not believe in reincarnation, one would be hard pressed to see the world as anything other than extremely unfair, to which some people are born into not just significantly better material circumstances, but also better educational, justice, fairness, looks, and health situations. While our Creator asks nothing more from us but to do the best with what we have, circumstances can make this extremely problematic for certain people and hence it would appear to be inherently unjust.
So too there are people, that have remarkable skills or inclinations even at a young age for medicine, mechanics, music, mathematics and so forth, so much so that we consider them to be child prodigies or similar. In a significant amount of cases, the parents of such children, wonder where these talents originated from, because they know in their heart, it was not in truth from their parenting or upkeep, instead it seems to have come from within the child, itself.
The best explanation for the reason why there are certain powers and predispositions inherent within each one of us has everything to do with recognizing that while the physical shell of our body changes from life to life, our soul remains consistent to what it was in previous lives. That is to say, if you have previously demonstrated a high degree of skill as a practitioner of medicine, than all things being equal, this same talent will be there in your present life like a rich oil well, available for you to tap back into it.
Not too unexpectedly, our lives are a mixture of good as well as bad habits, good as well as bad decisions, so that when re-entering this life after having exiting a previous one, those bad traits that we have previously demonstrated of perhaps lacking in patience, having a hot temper, and so forth, are carried with us, the same as if they never left us. This, more than anything, is the reason why reincarnation exists, because we know whether we want to recognize it or not in this world, that in order to get right with our Lord, we have to have demonstrated right actions and behavior in this dimension.
For those that dismiss reincarnation, recognize this important point, if you were excessively jealous, covetousness, prideful, lustful, and so forth on this material plane, do not think even for a second, that somehow in Heaven, that these traits of yours will miraculously disappeared, as they won't at all, but rather will be seen to be dark clouds that perpetually follow you. Therefore it is these faults that will preclude you from truly entering into holy fellowship with our Creator, not because He will not accept you, but because you recognize that you still have work to do in order to climb that stairway into God's heart and Heaven.