The ancient Egyptians were obsessed with this concept, but we seem unconcerned.
Blockchain is remarkable because it conveys what is possible when intelligent people work towards a cumulative goal. We live in the age of information and technology -- knowledge is available, and mankind is now capable of so much more than ever before. However, we waste so much of our ability chasing money. If we were to work together to discover the reasons for life, perhaps we could understand it.
I dont want to die without knowing what this is/was. There are tons of resources available online, there are scientists, the LHC, preachers, etc -- but the truth remains, that nobody really knows. If we can understand it, perhaps we can control it. If we can communicate with our creator -- perhaps we can understand why. Perhaps we can reason, understand why, understand how to evolve, defeat pain/illness/death.
the truth is, we already know, for the most part atleast what we are and why we exist.
I will probably burn in hell if im wrong but i can 100% guarantee you that there is no god. We have no creator (other than maybe the first cell in the universe?)
as for the two questions
We are the brains floating in our body right now, no we dont have a soul, no we are not the entire body, it may be hard to accept, but the only YOU part is your brain.
and as for the how we are part- a random asteroid/meteor/meteoride hit Earth a couple billion years ago and it happened to have the essential ingredients for life, and earth also happened to be in the goldilock zone.
If you dont believe that that tiny probability happening actually happened, know that there are billions, no quadrillions of stars out there, and almost each one of them has a planet, multiply the numbers and we have a near 100% chance of existing at some point (we as in life not humans)