I don't know. No one does.
No one can tell you why there has to be such a thing in nature as quantum mechanics, relativity or this maddening nesting of complex structure within complex structure. Some physicists believe that to ask these kinds of questions just leads us into a never-never land of circular reasoning which always gets around to something like " The reason that it is this way and not some other way is that, if it were the other way, we would not be here to pose the question in the first place!"
If Nature were any simpler, or the universe any smaller or younger, life as we know it would have been impossible. The laws we seem to uncover are just complex enough for organic life to be possible, but not so complex that they seem chaotic and random. As conscious beings within this universe, we seem to live on some kind of razor's edge within a much larger arena populated by an infinite number of other ways that 'things' could have turned out. A 1 percent change in any of the three constants of nature; the speed of light, Planck's constant, or Newton's constant of gravity, would have eliminated organic, carbon-based life from this universe.
Can consciousness occur in some other host medium that is not organic? Would such a host medium have naturally arisen in the 'new' universe? It is hard to imagine a proto-computer made of silicon somehow self-assembling itself without something like the equivalent of a DNA molecule. It is amusing to speculate upon these matters, and whether consciousness could arise in other kinds of universes, but ALL of such speculations are non-scientific and beyond testability.
Some people are welcome to argue with me that, in addition to the physical world, there exists a spiritual world with sentient beings and its own 'natural' laws. So far as science is concerned, these worlds are outside the realm that science can study. Anything that is not a feature of the natural, physical world of forces, fields and energy, is in the 'supernatural' world and outside science. This includes astrology, psychic phenomena, fortune telling and, yes, the issues of whether the soul, angels, demons and God exist.
Religion and science are totally incompatible world systems. They do not use the same methodologies, and standards of evidence and proof, to settle disputes. Nor should they probably be asked to.
Science is about developing and improving our understanding of the universe as we see it. This is a sequential, tedious, and imperfect process in which ideas are discarded and new theories fashioned from the embers of the older ideas. Despite what you may have been taught, Science is not about the search for any kind of Absolute Truth about the physical world. As practiced by the everyday scientist, science is about the search for better and better ways of describing how nature seems to work and the underlying rules that seem to govern this grand universe. Some of these 'ways' can be formulated in mathematical rules and theories that to many non-scientists, almost seem like absolute truths. Scientists recognize that, even statements such as nothing can travel faster than the speed of light, may eventually be found to be not so absolute in the future even though we are currently clueless how that might happen, and certainly our data in the 20th century shows no room for such a possibility.
Religion is about how to achieve salvation, and usually has nothing but scorn for the tedious details of how the physical world works. This is probably also the way it should be. Religion must promulgate a set of absolute rules that are indisputable by divine ordination, otherwise humans will feel uninhibited about behaving in any way they choose. This could have devastating consequences for the long terms stability of human culture, and the very survival of the human species. No relativity, or toleration is permitted. There must be a penalty for transgression; to be suffered in the next life or at Judgement. Laws are obtained from a single divine event or set of events that cannot be independently confirmed because they occur by 'divine revelation'. These laws are statements which are not subject to revision by presenting new evidence that contradicts them.
Once you understand that these systems of thinking are not compatible, you are released from having to constantly defend one system by trying to use the methods of the other. If, however, religion tells you that you can walk out the window at the 35th floor, or over harvest the fist in a lake without any long-term ill effects, these are clearly situations where one system of thinking has over reached itself.