Too lazy to read the whole thread so I'll just add my input.
So basically you're asking "The Why?" ; first of all, welcome to a more spiritual world. It's good to ask yourself that question, we're touching a period where spirituality will play an important role for mankind imo : we've had a century of crazy technological & scientific growth but we've lost something on the way, or we realize we lack something we didn't need so far.
When I say "spirituality" I'm not talking about religions, I'm talking about inner peace and humility, knowing how small and irrelevant we are, how unlikely and beautiful the phenomenon of Life is, and how fucking things up will just end our existence and just leave space for something else. We're not important, we're not "god's creation", we're not the center of all things. We're just a tiny part of one huge ass thing.
So, there's no "Why". The "Why" to Life is Life itself ; but our human purpose is for us to create. We could be shepherds ensuring the balance of our ecosystem here, we could go spatial and be witnesses to the Universe, we could be individualistic selfish beings trying to accumulate the biggest amount of useless shiets for no special reason but having the most, we could be a disease and fuck everything up with no purpose until we erased ourselves... All you need to discover is what will make YOU live your life happy and with little regrets in the end.
Personally, and knowing we're a social species, I'm trying to make myself happy by making others happy, more aware of our condition and the conscious choices our survival requires, through art and communication. Trying to do what I can to change the world in the direction I judge the less harmful from a social and biological point of view, even if it's vain, I do what I love for the things I know to be true.
We're at a point where humanity will either become nihilist or spiritual. You choose.