If someone ends up in Shanghai, in particular in a hostel that calls itself a ship for its bunk-beds can meet people of different countries. These folks there in Shanghai speak the common tongue. For this is not Middle Earth but simply The Earth that language is not the Westron but the English language.
Its nice to speak German or French but in Shanghai the only use of it is the ability to say ‘Ich liebe dich’ to the German girl instead of ‘I love you’.
There are giant multi-nationals with French or German background but they require English just like the hookup in Shanghai.
English is a peculiar language. It has many standard forms, more than one ortographic standards. Some English dialects are so far away from each others that they are hardly mutually intelligible for native speakers.
There is also the international English. For a simple example this blogpost here is written in that language.
International English is one of the very few languages that can be spoken on different levels ranging from pidgin up to the rather funny dialect of Mr. Barroso.
Many people in our beloved Hungary think that English is easy to learn. No it is not. Indeed it is hard to climb to a level where no one thinks you are native, nor do you endeavor in to the realms of sophisticated grammatical constructions. You are just able to comfortably express your thoughts in a way that no one thinks you are talking about melons while you think you talk about apples.
Good international English gives you some safe feeling, the ability to think about the subject matter and not about the way of expressing it.
It does not mean that you speak good English or you can write in a nice concise way. Nope.
But if someone thinks that this is a level one can easily achieve is a fool. Well, they are fools anyway.