The ideas of heaven and hell were not adopted until well after religions were formed. The actual idea was adopted by religious institutions after man-made texts were introduced and the need for punishment and reward were required to justify the writings and teachings in each book. Theologies that remain relatively untouched to this day reflect this and the older texts that have been found reflect this as well.
For example: Jews don't really believe in an afterlife, they believe that you need to live by God's word and do his work on Earth as best as you can. Also, the oldest known reference to Hades the person was a "God" that was the keeper of the path to the underworld, simply there to ensure a one-way street. As time progressed, he turned into the "Devil" overseeing Hell.
Further proof can be found in religious texts throughout the years changing Hell from nothing to nothingness, then a cold place, then a fire laden underworld, then the 9 rings of Hell, then back to fire and brimstone...It changes constantly.
If you could remember your life or come down as angels to your family etc. There would be strife caused both down here and below. People jealous of the fact that some would get divine intervention and preferential treatment. You couldn't be allowed to go up there with any earthly memories else it would totally ruin the concept of a place free from worldly worries and such.