About English vs. other languages:
http://cnt-ait.info/article.php3?id_article=54
As previous stated, you wont get far on the intenet, work and other places if you dont know English.
Completely false. On the contrary, you'll go to places where you wouldn't have been if you speak/read only English! Try Russian, Dutch, Portuguese, Arabic and you'll discover an Internet much more rich than the small one you know!!!! Never been on .RU, .TW, .ES, .PL, .PT places?
If there were only 1 language in the world(…)
It rings me a bell: the story of Babel. I'm not sure that there would be no language barrier. Just see: within the same city, people who don't have the same culture do not understand themselves as expected. And not to mention the difference in thinking between men, women and children.
I'll bet if you asked all users on this forum, to write down the language they love the most, English would not be on the top.