Why is England called England? “England” means “the land of the Angles.” It is not named for the country’s jagged coastline but for some of the people who live there.
The original inhabitants were not from England but from central Europe and were called Picts or Celts or Britons. It is probably not fair to depict them as barbarians, but that is sometimes done. The barbarians have since been pushed to the fringes of the British Isles and still exist as the Irish, Scots, and Welsh.
In the first century AD, England was invaded by Romans, whose troops came from everywhere except Rome.
Then in the fifth to sixth centuries, England was invaded by Jutes, Angles, and Saxons (sometimes grouped together as “the Anglo-Saxons”, the Jutes somehow being left out). They came from northwestern Europe, the Jutes from Jutland, the Saxons from Saxony, and the Angles from Schleswig-Holstein. Once they had arrived in Britain, the Anglo-Saxons intermarried with the Britons. A Briton would see a cute Angle, and the rest is history. Or geometry. If a Saxon fell in love with the same Briton or Angle, that would create a love triangle. The Saxons seem to have been preoccupied with sex, naming various parts of England Wessex, Essex, Sussex, and Middlesex (you can insert your own comment here). But there was no Narthex, the north of England being too cold and wet for such activities.
England was next invaded by Danes, who were actually Vikings from Scandinavia. They also interbred with the previous settlers, although this was not necessarily voluntary, the Vikings main skill being raping and pillaging.
In the 11th century, England was invaded by the Normans from northern France, although they weren’t actually French (they didn’t have enough gall), but rather Vikings from Scandinavia. The Normans were cruel, violent, and very warlike. This is possibly because they were angry over the fact that their parents had named them all Norman.
The Angles were named by a pope in Rome who saw tall, blond slaves captured by Roman armies and decided they looked like angels. They weren’t actually angels (see the above note on geometry).
So, why did England end up being named after the Angles when they were only one small group of the many people who invaded England? No one quite knows, but I suppose it would have been too difficult to name the land Pictromanjutanglesaxondanenormanland. No one would be able to spell it.