Why are the names not mentioned?
Why would they be?
Considering Islam believes that many thousands of prophets were sent down, would it really have been productive to have listed thousands of people's names and tribes when they had no bearing on how to live righteously or on the history of the people who received the message?
And let's suppose allah sent messengers to these areas. Why is it that their belief system is so different from Islam? Why did god send them very different message from bible and quran?
In Islamic belief, that has nothing to do with the prophets, but with people distorting it for their own gain or by accident.
Why is it that native Americans believed in Spirits, and Mother Earth?
See above.
Why weren't they sent down a book which also explained how Moses parted the sea or how Noah built the ark?
Because they would think "who is Moses", "where is this land", and so on? It would not be beneficial to them. And that's if we don't suppose that they did do it. There would be little to get from the story, would there, besides more questions?
And writing. Well, writing... can have issues when few people can read or write.
Why is it that their belief system is totally different. Their concept of god is completely different from both Islam and Christianity aswell.
See above.
They believed in universe, Mother Earth and nature. They would praise nature,
There is no homogeneous "native Americans" belief, so this is incorrect. One also has to define "nature". What does "believe in universe" even mean?
Well, yeah. Already covered this, as well.
Is there a difference in concepts between "Dios", "Dio", "God", or "Gott" to a Christian? No, just different words. Not to mention Islam believes in many "names" of God; Ar-Rahman, ar-Rahim, al-Malik, al-Quddus. So, yeah.