Übergeek 바둑이:

"would have seen animals die and say "I will die some day, what will happen to me then.""
..... Not at first, as such the first humans would have seen death as a natural part of life, it's not till later when mankind would have questioned death.

"has plagued humanity since its earliest beginnings, because once we die we have no sensory perception of the universe, and the living have no way to communicate with the dead."
..... I'd say we'd have a better perception of the universe as we are no longer tied to a degree a fixed point. As with no means of communication.. since a certain funeral I'd have to disagree with that.

"Instead human beings became so attached to the physical world that once the body died, the person would "reincarnate" in a new life somewhere else. This cycle of death and rebirth led to great suffering in living beings because as we live we lose all those things we are attached to. Then the concept of "nirvana" and "enlightenment" came in. If a person became enlightened, the cycle of death and rebirth would end."
........... Quite frankly, you've missed the spirit of it all. The reincarnation was until the person learnt to be nothing and as such be. Joe would still be Joe, yet things would be in perspective. As they said in Greece.. an unmoved mover.

"You cannot be sure that God exists and that God will save you, so organized religion attempts to give people that certainty."
..... Now this is tricky. To me the answer is both yes and no at the same time. God as in existing as some man... no. The male and female form used in judaism as such is just indicating role and form of God in terms of our relationship. Though they tried in the formation of the RCC and doctrine to ban the idea, God is just an energy. As such the whole universe comes from that energy and is such that energy and then we get back to the self again. How do you describe it? The covenant with God is such that things will come your way to make you see what is clouding you.. some aspect where some believe God will stop anything bad happening. Well... Christ didn't want to push it in the desert As to belief on existence... Well some claim that such is the calm that can be achieved at times that they feel something. this thing cannot be described it just is.

And yes.. blind obedience to a set of rules is wrong. A person is to come as such and join with God as a matter of free will. No-one can teach you that, and if they try and force it on you then that is realistically a mortal sin.

Funny world.