There are an estimated 37 trillion cells in the typical human body. If you have ever taken a biology class, you learned about the generic animal cell and its organelles. It is important to keep in mind that these organelles are all composed of macro-molecules and molecules are simply aggregates of atoms. The point I want to emphasize is that biological systems consist of abiotic (non-living) matter. When a biological system dies, it is degraded by detritivores or heterotrophs that rely on other organisms for sustenance. Some of the matter returns to the ecosystem in the form of abiotic (non-living) matter. Why do you think we eat food so often? We use the organic matter in food to repair and sustain our own biological system by incorporating the molecules in food into our own bodies.

One commonly cited factoid is that the human body consists of 70% water. Just because this water happens to be in a biological system doesn't mean there is anything special about it. It is the same abiotic matter that has been part of the water cycle on earth for billions of years. The water happens to be trapped in a biological system at the moment but it will be excreted and recycled back into the environment through the water cycle. Carbon and nitrogen are also major aspects of biological systems and they are also cycled through the environment. Do you remember learning about the carbon or nitrogen cycle in biology class? If not then I suggest you read up on these ecological cycles that all life is a part of, including humans. The takeaway from this paragraph is that matter and energy is not created nor destroyed. It is recycled into the environment in various different forms.

The information above is hard science that might be useful to glean insights into the philosophical questions you are asking about. With that said, I will give you my perspective on these philosophical questions because you asked for it.

I personally do not believe consciousness can be maintained after death. For 13.7 billion years prior to birth, I was oblivious to what was happening in the universe around me. Every night when I go to sleep, I am oblivious to what is happening around me. I lose my perception of time when I am asleep. I had no perception of time prior to my birth. It is clear that you can only be aware of your surroundings while you are awake, whatever that means neurologically. You cannot maintain this 'conscious' state if your biological systems stop functioning. You can't even maintain this conscious state constantly while you are alive because you have to sleep eventually. Furthermore, a comatose patient is not conscious of their surroundings despite having functional cells throughout their body. What reason is there to assume that they would be conscious after they die?

Some of the other questions you are asking don't make sense to me. Try rewording your questions that I didn't answer in this post if you want to hear my opinion on them or if you want me to clarify anything I said. By the way, nothing I said should be misconstrued as evidence of 'reincarnation.' There is no evidence for a soul. For example, identical twins born from the same zygote are not privy to each others internal thoughts.