I believe (sort of) that we are literally every person. In the 'afterlife' there is no time, and so you can reincarnate into your own child, or your parent, or someone who lived 1000 years ago.
And I believe that is exactly what we've done. One soul, reincarnating over and over again, into multiple different people (every single person in fact) over millenia.
We live every life and die every death, and so it is that what we do to others is quite literally what we do to ourselves.
I also believe we do have consciousness before we are born (obviously according to above belief), but that we so easily slip in and out of amnesia without questioning (ie. ridiculous dreams that we don't really question while experiencing it - ie. flying), and that incarnation in a body is like accessing the internet through a computer.
Using that analogy, from the internet's (world's) point of view - if your computer (brain) malfunctions or shuts down - you are sick/mentally ill/demented or dead, and so we say consciousness is in the brain. But in reality only your interface has stopped working. You (consciousness) are still intact and just need a new computer (body/incarnation).
I say these are sort of beliefs because I go back and forth. Part of me thinks there is nothing, and really welcomes that thought. Not sure if that is just depression talking though.