Now the first burden of proof seems easiest. Is there anyone here who disagrees that all languages are very related and that in the beginning there was only one language?
I very much disagree.
It is possible that in the beginning, there was only one language. It is by no means certain. Humans started being able to speak about 100,000 BP. At that time, they were apparently all in Africa. They left Africa about 70,000 BP. The area today in Africa where they were over those 30,000 years is an area whose inhabitants speak many different languages, and this is in a time when telecommunications make for fewer languages than the world had in the past. It is probable that the original speaking humans didn't even know of the existence of all of their fellow speakers, but only those speakers in their own tribes. In all likelihood, language developed independently in very many places and there was no single original language.
Furthermore, it is most certainly not the case that all modern languages are related. No modern language has an ancestry that can be traced back further than about 10,000 years. At 10,000 BP, there were people living in Eurasia, Africa, Australia, and America. These people did not all have contact with one another and did not all speak the same language. They had many languages. There is no relationship betwen Australian languages and European languages. There is no relationship between sub-Saharan languages and languages of the northern Pacific coast in North America. There is no relationship between any of the thousand or so languages of Papua New Guinea and Basque. Some languages in the world are related to others. No language is related to more than a miniscule number of the world's 6000 or so languages.
So I disagree wholeheartedly with your first contention.
1. Arabic has a complete organised structure of roots, that is to say, the roots meet fully all the needs of human beings in the field of expression; the other languages are not so fitted.
Even if what you were saying were true, it would actually tend to indicate not a natural language, but an artificial language. Kind of like how Esperanto has a perfectly regular morphology. Making this claim actually hurts your case.
2. In Arabic, the names of the Divine Being, the names of the principal constituent parts of the universe, of plants, animals and minerals and of the members of the human body, possess, in the why and wherefore of their contents, deep philosophy and learning. Other languages can never equal Arabic in this respect.
"Deep philosophy and learning" is neither specific nor measurable enough to be meaningful. No one can prove that the Arabic lexicon lacks "deep philosophy and learning," but at the same time, you cannot prove that the lexicons of other languages lack "deep philosophy and learning."
3. The additions and the roots of Arabic words are perfectly organized. The scope of this organization, by linking into one philosophical chain, all the verbs and nouns, belonging tot the same root, points out their interrelationships. This is not to be found, to this degree of excellence, in other languages.
Again, if this were true (and it's not), it would be more characteristic of an artificial language. Think Newspeak from
1984.
4. In Arabic expressions, words are few but meanings are many, that is to say, the Arabic language makes use of alif, laam, and nunation and the sequence of words, in such a way that to express the same meaning the other languages need a number of sentences to be linked up for the same purpose.
For your claim to be meaningful, you would have to show not that Arabic uses fewer words to express a given meaning than
some other languages, but that it uses fewer words than
all other languages. That'll be tough. Languages like Inuit and other agglutinative languages frequently uses a single word to express what would take a couple of sentences in a language like English. Arabic, being the same class of language as English in this regard, hasn't a prayer of beating highly agglutinative languages on this count.
5. Arabic possesses roots and expressions which are the perfect means of portraying the most delicate and deep things of the mind and human ideas.
What's the Arabic root that perfectly explains the relationship between Brahma and men's souls?
What's the Arabic root that helps us differentiate clearly among bodhi, kevala-jñana, and satori?
What's the Arabic root that perfectly explains the doctrine of the Trinity or the concept of transubstantiation?
Which Arabic root will help me see the difference between wyrd and ørlǫg?
Which Arabic root (and I'm assuming you're talking here about classical Arabic) will finally help me understand general and special relativity?
These are all rather delicate and deep ideas of the human mind. Does Arabic have the perfect means of explaining them?