The problem of biology
The ancients, obviously, had no knowledge of modern biology. So, there are a number of misunderstandings inherent in many ancient teachings.
For example, until quite recently it was believed that humans and other animals grew from seed - like crops. The man would plant his seed in a woman and if she was fertile a baby might grow. Clearly the seed was of no use on its own so the process depended on a fertile woman and the 'seed' then being endowed with the mystical 'spark of life'.
This analogy seemed obvious to agrarian cultures familiar with dry, seemingly dead, seed springing to life mysteriously in appropriately prepared soil.
In earlier hunter-gatherer societies, inheritance had often been matrilineal, because we more obviously came from our mother and she from hers and so on. But in these more advanced societies, babies now belonged to the father from whom the 'seed' had come and so inheritance became patrilineal.
For example, in Chapter 1 of the First Book of the Christian Bible (Matthew Chapter 1) Jesus' ancestry is traced back to King David through the male line, as he needs to be a Son of David to be the prophesied Messiah. Luke makes the same claim for him but by a different ancestral route (Luke 3:23).
This fundamental misunderstanding of the biological process has influenced laws of inheritance, property ownership and marriage in almost all human societies with agrarian roots, right up until the present.
Today we understand that babies develop from a single live cell that comes from our mother. We know that these specialist cells are incomplete and non-viable unless fertilised (we still use that term) by a single living sperm cell from our father. We now understand this mechanism so well that we regularly practice in-vitrio fertilisation (IVF) to assist childless couples.
Thus, we know that a 'virgin birth' in which a god inseminates (inserts his seed into) a woman who gives birth to a god is not possible, unless we allow a unique relativistic exception, in the case of heavenly matters, to the usual definition of the words: 'virgin', 'father', 'mother' and 'conceive'. Any outlandish claim can be made nominally true if the words used, like 'love' or 'have sex', have fluid meanings when gods, or US Presidents, are involved. Thus, the question of such a story's 'truth' is not biological or factual but semantic.
Similarly, we know that there is nothing dead involved in a fertilisation and no 'life' is created at conception. Each cell involved has a living ancestry going back to the first common ancestor of all plants and animals on Earth.
Modern understandings have allowed us to reach a more sophisticated biological model in general. This is not limited to human biology but that of other animals, plants and bacteria, as well as the functioning of other symbiotic factors such as viruses and prions.
In my lifetime we have gained an entirely new understanding of the mechanisms of DNA replication and of 'life' itself.
But it is clear in hundreds of references that this knowledge was obscure to, and entirely misunderstood by, the ancients who wrote the holy texts, allegedly channelling the words of an all-knowing God.
It seems trivial to anyone with a glimmer of modern biological knowledge that this 'life' mechanism is inherited as cells divide and is continuous from the distant past. But there are many ancient references to life being 'created' anew.
We also know that the life of an individual cell is shorter than that of the being of which it forms a part. For example, an adult human is a colony of around 35 trillion cells (including symbiotic bacteria). An awful lot more are required to make a blue whale or giant sequoia. In humans these cells are continually dividing to replace the 50 to 70 billion cells that die each day in each of us. A lot more die in a blue whale.
Ancient texts have quite a bit to say about spiritual rebuilding but I have been unable to find any reference to our being continuously rebuilt physically. Yet it's knowledge that would seem to be pertinent to religious memorials and burial rites. Consider the fate of all those cells from which you were formed as a child that were long ago replaced and replaced again. As you aged you simply brushed them up as dust or flushed them.
The living may very legitimately mourn a loved one, perhaps at an appropriate memorial or wake; but why treat their last body any more reverentially than they did themselves with its younger incarnations?
We have excellent evidence for the correctness of our new biological models and beliefs. If they were not a better representation of reality than we had only a century or so ago then modern medicine would not work. Conversely, we know that ancient medicine, based on false suppositions, misunderstandings, and florid imagination, seldom did.
Although some ancients suspected it and others denied it, as far as we can tell all animals and plants on the planet are related. This has been confirmed by very extensive DNA analysis encompassing almost all living things we have found on Earth. So there is no 'natural' hierarchy in which humans have a special place. We all (living things on Earth) belong to a single biological family of the same age.
Thus, the hierarchy we have imposed on our biological relatives is entirely for our own (human) purposes.
It's like deciding what is a weed in your garden? Why, it's any competitive plant that you don't want there. So, pull it up and put it in the compost!
Each species has evolved by degrees as a result of competition with other relatives, all from that first common ancestor.
By nature, all these species compete for a biological niche. If one is not present or is wiped out by disaster another will evolve to take its place, for example the recently evolved Fossa, as top top predator on Madagascar. All animals and plants impose a hierarchy of their own: what's dangerous; useful; or good to eat; or even - simply attractive or amusing. This latter attribute is often exploited by plants to control animals - thus we perpetuate roses.
We humans try to eliminate things that don't suit us, like smallpox (and until we became more enlightened wolves, tigers, bears and sharks), but try to save cute things, like minke whales and pandas. We also have plant and food preferences. We eat beetroot but not tulip bulbs; sugar cane but not pampas grass; and goats but not (usually) cats. In Australia but not in England we poison blackberries and infect rabbits with fatal diseases.
The ancients often had a special list of edible or objectionable plants and animals and even how to prepare the favoured ones to eat or sacrifice. But it varied from religion to religion and displayed no awareness of the entirely arbitrary nature of human preference.
We now realise that none of the creatures 'great and small' was specifically created for our benefit, as some ancients argued. If we wanted to redesign something for our benefit, we had to do that for ourselves - think of domesticated animals. Now we can do this more efficiently, like the recently designed crop that now provides much of our vegetable oil: canola (named for the Rapeseed Association of Canada).
Each of us is a complex cellular colony. Individually all such cellular colonies, like you and me and the giant sequoia, will eventually fail for some reason and die. But life is everywhere here, in our case, in common with other species, perpetuated through our offspring.
To reiterate, viable life is a matter of information and organisation. It's not repeatedly recreated. It's inherited from the living. But like any message or organisation it can be corrupted or lost. Then we die. But elsewhere cells continue to divide and life goes on relentlessly.
It is not as the ancients thought: 'a matter of life and death'. There is no new life. Life is continuous. But there is continuous death. Individual cells die all the time.
For us multi-cellular colonies, in common with the blue whale and the giant sequoia, organisation is critical to survival and in the case of us and the whale, to memory and awareness. When that organisation is sufficiently disrupted by old age, disease or trauma, death results and: it's final; the end; nothing.