If you do not like odds of 50:50 that there are other realms beyond this one, ARS, then I will restrict myself to saying that the odds are unknown. Unicorns, if they exist, will exist in this world, and are irrelevant to what we have been discussing.
It is important to understand that an afterlife - if any - need not be as described by Dante or Milton, and that celestial beings – if any – need not be a creator God.
I have seen the suggestion that if God – or celestial beings – do not exist, then they could evolve.
Which leads to my next point. Life often improves its environment. Photosynthesising organisms produce oxygen as a by-product, and unwittingly benefitted higher forms of life. When plants colonised the early land on Earth, their roots stabilised the ground, thus dramatically reducing erosion, and microbes turned earth into soil. Rabbits dig burrows and birds build nests. North America is much better to live in now because of the efforts of generations of European settlers.
The next step is immortality, either in this world, or beyond. Beyond may be a realm of spirit, or it may be material, but better. The idea of parallel universes goes back over a hundred years, and H G Wells used the idea in his 1922 novel Men Like Gods. The Fermi Paradox may come about because once advanced aliens reach a certain stage of technical development, they find a way to migrate to a better parallel universe, or to a spiritual realm. That is why we do not observe alien spacecraft flitting through our skies, although I know there are other explanations.
Cryonics is an attempt to gain an extended life in the same body, but improved, in this world, in the future. It is a form of reincarnation.
The late British astronomer and science fiction writer Fred Hoyle wrote a novel Black Cloud which proposed a sentient interstellar gas cloud which aimed itself at our Sun and wrapped itself around it to get energy. Hindus are likely to accept such a gas cloud as a celestial being, and would point out that such a celestial being, while ostensibly immortal, still depends on the universe, and will die if the universe dies.