A belief in reincarnation is probably spontaneous for human beings. It is a feature of most hunter-gatherer animistic religions, and also of 'Eastern' forms of paganism such as mainstream Hinduism and Buddhism.
The basic idea is that after death of each currently-alive human, each human soul returns to earth in another body - and that each currently-alive human being has a soul which previously inhabited other bodies.
Thus, in the normal situation, souls circulate through incarnations; and life is a matter of cycling and transformations.
(In different traditions, this cycle of souls or a particular soul may be constant; or may have a meaning or tendency - towards upward progression or downward degeneration.)
Since I do not believe that reincarnation really happens (or, at least, that reincarnation would be a rare and singular occurrence, not the norm) - then there is a need to explain why so many people feel that reincarnation accounts for basic perceptions concerning the nature of life.
I just have a couple of observations or suggestions based on the idea that the reality of reincarnation may be a consequence of 'misinterpreting' the meaning of true intuitive knowledge.
For example, the feeling of a particular affinity between individuals born in different generations may be due to a pre-mortal, pre-incarnate, spiritual relationship - and that incarnation of pre-mortal spirits may be purposive: that the earthly reality of human relations is in some way a microcosm of the pre-existent spirit reality of divine relationships.
(The reality of a pre-mortal spirit existence has been a minority, although sometimes prestigious - e.g. St Augustine of Hippo, view within Christianity throughout its history - and is currently mainly represented among Mormons.)
This would mean that we are non-randomly incarnated to be born by particular parents in particular situations and with a particular 'network' of potential-deep relationships (not all of which may be apparent). But this is not (as for reincarnation) based on what we did in past lives, but what we are 'destined' to do in this mortal life.
(Bearing in mind that we may choose to defy our destiny, or it may be thwarted by the choice of others or by accident.)
Also, the survival of the soul after death seems to be a near universal intuition (which can, of course, be over-learned and suppressed as is usual among modern Western adults); and this intuition may be interpreted not as a step towards some period of life in a post-mortal spirit realms and then resurrection, but as implying that the surviving soul returns to earth in some other form.
(If there is no concept of a heavenly realm, or a spirit underworld, then the only thing a surviving soul could do is to return to earth: either as a discarnate ghost, or by taking another body.)
Also, our intuitive sense of a need for a great deal of spiritual progression, that we are actually grossly imperfect but are supposed to be perfect (or much better than we are) - suggests more learning and development is necessary than can be accomplished in one mortal life.
The interpretation of this intuition may suggest that soul would need to return for multiple lifetimes or attempts. Christian theology regards this perfecting and progress as the work of Christ; and some also allow for further spiritual progression in the state that comes after death.
On the one hand reincarnation is optimistic, in the sense that this mortal life we currently experience is not our one and only chance; in another sense and at a deeper level, reincarnation is pessimistic because it devalues this particular mortal life as non-essential, optional, just one among many.
Both reincarnation and my own theology demand some kind of rationale and metaphor to explain why the reality is non-obvious: why do we not know spontaneously and exactly where our souls come from and go to?
If the feelings are built-in, which they are; then why not also the understanding of what these feelings mean?
Why must this be puzzled out, guessed or made the subject of divine revelation?
The various answers are the basis of the various theologies.