The body is temporary, but the soul is eternal. You are your consciousness. As your soul is immortal, you are also immortal. The soul connects to the body and makes it conscious. Sometimes the body can be alive, but without the soul and consciousness, it would be like being in a coma or having amnesia. Some people with Alzheimer's and dementia are still alive and perform basic functions, but their soul has left the body. As you communicate with them, you may notice that the soul is not there. It can return for a short while, but then it will leave again, maybe because the life is not interesting, or maybe the body has become damaged and the soul has difficulty staying connected to the body.
The soul is multidimensional and much bigger and much more complex than the body. The body cannot contain the whole soul; it only connects to a much larger soul. The soul uses its life in this world to gain experience, learn lessons and improve the world.
Although human life is short, these experiences and lessons are imprinted in the soul and remembered forever. The personality developed in life remains with the soul and is immortal. The body dies, but the personality and its memories remain. Since lives are short, the immortal soul incarnates many times.
In every new incarnation, the soul gives the body its character, which is why even identical twins often have very different characters - because even identical twins have different souls. On the other hand, different incarnations of the same soul have similar characteristics, yet with every new incarnation, the character develops into a new shape and a new personality is developed.
The personalities are somewhat similar, but since each life is different, each new personality develops differently. Every new incarnation is in a new period in history, learning new lessons and rising to a higher level with each incarnation. Every new incarnation develops a new personality that remains forever. They are eternal. All new personalities join the oversoul and unite with it. Yet, when desired, they can step out and act independently within the spirit world. In other words, different incarnations of the same soul can behave as one or independently at will.
The process of reincarnation starts from the soul choosing the father and the mother. The soul chooses the genetics for the body.
From the point of view of human biology, the recombination of the parents' DNA in a child is random. The child always gets 50% of the mother's DNA and 50% of the father's DNA at random. Yet, from the soul's perspective, these random events are under the complete control of the soul. It can pick and choose which genes are received from the father and which genes are received from the mother.