Why did the American Revolution occur and were the rebels justified in revoluting

All events in the history of humanity are the consequence of hundreds of other events, which accumulate and reach their climax in a historic moment. One clear example is World War I, which started with the assassination of the heir to the Austro-Hungarian throne, Franz Ferdinand, Archduke of Austria on the 28th of June of 1914.

Something similar happened in the American continent with the revolutions that sparked from North to South. The first of them was the American Revolutionary War, which officially started in 1775 and officially ended in 1783. However the key players were not Spain and the Colonists, but the English, the French, the Dutch, the Spanish, the Colonists and the native north Americans.