Jovaro,
Please let me answer your question in two parts.
Let's first think about the Bible. Most people think of the Bible as a series of nice stories. Christians even think of it as if it were a treasure chest of precious and beautiful gem. Most believers and non believers approach the Bible as if it has no form of its own and that we need to arrange them in some way to enhance their beauty and cause them to be better appreciated. We then tend to try and arrange the stories into some sort of outline.
The result of this approach is that most people can tell the story of say Noah's Ark, but can't tell you about why the story is there in the first place. Others know the story of David and Goliath, but what is it's relevence to the coming of the Messiah? Most of our Sunday Schools and even most church sermons you listen to, tend to have this approach. Pick a passage from the Bible and retell the story or talk about it.
So, you end up with the questions you were asking and most people ask. What is it about the Bible that makes it so unique amongst other religious books. If this were the only way I know to read the Bible, I probably would ask (and indeed have done) the same questions.
However, the Bible wasn't written as a series of unrelated stories and this is what makes it so unique amongst other religious books. I can trace Muhammad's life and experiences in reading the Qur'an. For each statement, there is a corresponding experience in Muhammad's life that he is questioning at the time of his "revelations". I can read American history and Joseph Smith's history as I read the Book of Mormon and the Pearl of Great Price. I can read Jehovah's Witnesses Theology in the New World Version. I can read words of wisdom in the hindu books and in the book of the buddha
Only in the Bible can you start before time existed and see how and why things are as they are, and I have explained this in other dialogues in the Muslim forum. I can provide the link if you like. When you read the Bible like that.. as a history as well as a theology or story book, it changes the way you read it. Sure, it is a series of stories in some ways, but it is a progressive revelation from start to finish which must be read in it's cultural and historical and theological frameworks. Read it like this and you will see the difference.
With the Bible, you have a progressive account of God's dealings with His creation, before creation, after creation and through history and into the future. In that respect it's totally unique to other books.
You asked about other cultures.. you are so right. Anyone can go into another culture and this includes Christian missionaries and share any holy book with them and they will tend to become excited by it and respond to it. However, in English we have a word called syncretism. What tends to happen, is that unless they undergo a complete change of world view as a result of what they hear from missionaries they will add the new teaching to their own world view and mix the two together.
Countless examples of this exist around the world, and I don't leave our own culture out either as many professing Christians do the same thing.
I spent time in Africa working in a mission hospital. Near one of the villages we worked in, there was a church belonging to a well known christian denomination.
In this church were many indigenous christians. However, the minister wore robes, they sang songs translated into their local language from English and they had a liturgical form of service. As soon as the singing started, people started swinging their hips and yet could do no movement. Once the service finished many rushed out to the local temple and completed the necessary rituals and sacrifices that the local animistic religion demanded.
What does this have to do with the Bible? In that same village, the bible translation team translated the Bible into the local language and the people read and heard the Bible for the first time in their own language and written in a culturally appropriate way. There was a massive reversal of thinking with no speaking required by the missionaries. The people said, "now we know God speaks our language."
You see Jovaro, in those other cultures, when people hear the whole gospel in their own language, they don't need missionaries. They respond because they know that the word of God is for them and not just for white cultural imperialists who bring the gospel wrapped in cultural ideology.
Where I live and work now, the same thing is happening. The Word of God speaks for itself. I don't need to go and preach the Gospel. As people read the Bible, they respond to God who speaks to them through the Bible. Can I explain it? Not in a human way. But I know the word of God speaks for itself to the heart. It's happened in my own life. We both know of others who have had the same thing happen to them without asking for them.
I'm sure this doesn't really answer your questions, but keep asking