Still, all Buddhists believe in rebirth, and if a rational being called Man is not the guarantor of knowledge (since man is reborn), then a Supreme being called GOD must be that guarantor.

Man is a rational being; if Man is supreme, who causes Man's rebirth? The science backs up that the mind has a connection to a higher power, and by strengthening that connection, one can become a supreme being. This is explained in some of the 52 points that I linked to and also by the phrase from the Bible "the Kingdom of God is within you".

Man is a caretaker of this Earth, and just as much Man decides the fate of a plant, some non-physical being decides the fate of Man's re-birthing.
Perhaps some extra-terrestrials are our "space brothers", they exist in the higher realms where there are no hierarchies, as discussed at length in the Phoenix Journals.

Science cannot change the cycle of rebirth; it is spiritual advancement which has made it possible for beings to travel here. The ones that travel here and are not sufficiently advanced in their connection to Source are monsters.

The Earth did not create your soul.

You are getting close; take a look at these essays from Lloyd Pye:
http://www.lloydpye.com/essay_interventiontheory.htm
http://www.whale.to/b/pye1.html

You can only be a creator if you are in harmony with the Laws of Creation. Otherwise, you will only create your destruction.