Let us for a moment discount all the many native languages in use in the Americas before European discoveries. Though we must not forget them in the overall picture.
The European invaders/immigrants who first colonised the eastern seaboard of North America came mostly from the British Isles, with a fair sprinkling of French, and German and Italian etc much later. As a result of conflicts centred in European power struggles, Britain came to "own" much of North America, and thus English became the language of general use. North America eventually split into Canada and the USA as a result of rebellion. But the English language was by that time well established and indeed most of the rebels had British or Irish origins, and some of the troops working for the King of Great Britain were German.
Almost no part of the world has "pure" ancestry, and we British have a very mixed ancestry, too varied to name in a short answer. Thus the "Britons" who colonised North America have origins from most parts of Europe, and beyond. The English language is basically Germanic in its daily usages, with many words from many other origins all around the world. American English has many Spanish words, e.g. canyon. mesa, lariat, rodeo, and names such as San Francisco and Las Vegas, which come from the Spanish occupation of southern parts of North America in times long past.