There are two questions we are reluctant to spend much time dwelling on. There is the questions of what were we before we were born and what are we after we die? Naturally, we are asking these questions from the position of having already been born and we are still not dead. But what if these questions could all be answered from the perspective of imagination?
In other words, what if imagination is not limited by either birth or death but is, so to speak, the theater in which births and deaths occur but also rebirth? As for first-person experience of this I think near death experiences (NDEs) are pretty impressive.
The infinite universe of imagination is difficult to fully grasp but not too difficult for us to assume that we are always reborn into an imaginary condition. This could also mean that the very stuff from which the imaginary is built remains ever unimaginable despite the fact that it is very real and authentic.
It is also to be understood that this infinite universe of imagination is a bad infinite universe insofar as we are unable to escape from it. This is to say, in other words, we must remain in it without any hope of finding a way out. If there is any idea of a heaven in such a world it would be the loss of our memory of how long we have been trapped in it. Every life would seem to be the first time and be the last time upon death.
I think all of this expresses the Buddhist idea of saṃsāra and also nirvana which is beyond the ken of saṃsāra. This reminds me of what Nagarjuna said: The ultimately true nature of the Tathagata eternally stays. The world of imagination is constantly changing, it never stays eternally. We only transcend the world of imagination when we intuit our true nature.