Even after talking this much you still don't get it. A language can never constitute one or two words, even at its inception it has to be 100s of words understandable by other people.
Yes, but this is a semantic distinction. You are appealing to the definition of a language as a complex body of syntax, grammar and vocabulary, to suggest that it is impossible for language to arise organically. However, this is a weak argument. Nobody is saying that language just popped out of thin air one day. It had to develop over centuries, millennia even. Nobody is saying "a fully fleshed-out language can be two words". What we
are saying, is that the faculties necessary for language genesis are shared among almost every human. What we
are saying is that people can develop spontaneous modes of communication, that can develop and become more complex over time. What we
are saying, is that languages develop from small beginnings. Two words become four, four become eight, eight become sixteen, thirty two, sixty four, a hundred, a hundred become phrases, phrases become sentences, become syntax, become grammar, become fully developed language.
Languages don't pop into existence overnight. Nobody is disputing that. They develop slowly in human populations through generations of people. However, they
do have their origins in rudimentary communication. It's like every other complex human construct: they start out very, very simple and develop over time.
1. It is for communication, if one individual knows a language but can not make the other person understand, then it is not a language because they won't communicate.
So French is not a language if only one person speaks it? I would dispute this.
2. A language can never be one or two words. If there's a new word, you have to use other words to explain the new word
I disagree. Babies learn words one at a time. We don't teach babies rudimentary language by explaining the nuances of of a word with verbosity. We point to an object and say "cup". And the baby learns "the thing with the liquid in it is called cup".
3. A language can never be one or two words. Communication is about understandable statements/sentences; one word sentences are very rare. So if we start a language and have one or two words only, we still can not communicate therefore we don't have a language
Again, semantic argument. Nobody is disputing that a fully formed language can consist of one or two words. I am disputing the idea that one or two words cannot develop into more.
4. If instincts and pheromones were working perfectly (for our ancestor)in terms of communication, why strive to develop words and their meanings?
This question doesn't make sense. You're assuming that I am saying that everything which is necessary for modern man to communicate, can be done through body language alone. That's not what I'm saying at all. That's clearly a false idea. What I am saying is that body language constitutes a good basis for people to pair vocalizations with gestures, and the vocalizations become words with inherent meanings.
If I shake my head to an infant and say "nein" (German for "no"), they'll instinctively grasp the meaning. The same is true if I shake my head and say the word "boogalooga". The word "boogalooga" becomes no. If I point to running water and say "shigi-wiggi", water becomes "shiggi-wiggi". If I lift a cup of water, drink the water, and show it to the infant, and say "shigi-wiggi boogalooga", it becomes "waterless". Ergo, it is entirely possible to create a new language and for a new human being to understand it, despite them having absolutely no real concept of language.
it is like i know Swahili and the people around me all know Swahili and we can understand each other perfectly when we speak Swahili, why should we strive to start creating another language (e.g. Germany) within ourselves?
Now you're talking about polyglots and learning new languages. It's not really relevant to the genesis of language itself. Language arose out of a need to communicate. If you can ALREADY communicate, you have no need to create a completely new language.