"Try to be happy while living, for you're a long time dead."
~Old Scottish proverb
I dunno. We're ultimately made of energy according to Einstein's formula, and since energy can't be created or destroyed, we have always existed and will always exist in some energy form. I think we're just on to another life.
I was born with past life memories, as was my younger sister, who kept referring to "when I was a boy.." Careful research of young children 2-6 yrs old, all over the world, remembering details, conversations, and recognizing people from recent past lives show the accuracy of their memories.
Many children remember being on other planets, being animals, even ghosts, etc. They didn't publish any stories that weren't verified, so even checked out the details the kids said they observed when inbetween incarnations, when they were ghosts.
The people studied all agreed that they themselves chose which babies in the womb to enter and inhabit, and when to incarnate. Many studies showed that people reincarnate in clusters..entire villages of people sometimes incarnating together, and sometimes remembering each other, especially under mild hypnosis, and the accuracy of the remembered details were verified.
They speculate that's what's behind the common feeling that you're already good friends with someone you just met, and maybe even for the feeling of "deja vu."