Old English was the language spoken by the Anglo-Saxons who invaded and settled in Britain in the early Dark Ages, driving the Celts out of modern-day England. They were actually from modern-day Denmark and Northern Germany. So naturally their language was quite similar to that spoken by Norsemen; it's actually more closely related to modern Icelandic than it is to modern English if I recall correctly.

And I'd have to disagree about what you say about animals communicating better. For one they can't get across as complicated a thought as humans because they don't have actual language. And while all members of a species know what certain calls mean, how widespread are most species? Nowhere nearly as widespread as human beings are across the planet. Take a bird from the West Coast of America and a related species from Europe and I can guarantee you that they won't understand each other.