British Colonial Theory of American History is Bunk

I no longer accept the modern historian dogma that is the British Colonial Theory of American history. Firstly, it's just a theory, which means it's no better than a guess. Also, if the U.S. was founded by British colonist, then how can there still be Britons? Why haven't the Britishists produced JUST 1 transitional document. They talk about the Declaration of Independence showing the transition from British colonies to an American government, but it's obvious that the DoI was written by a developed and existing American governmental institution known as the Continental Congress. The change from Continental Congress to our modern constitutionally authorized congress is just a micro-governmental change that everyone accepts can happen. But, no one has ever observed macro-governmental change in the real world, nor will they.

On a completely unrelated note, a Florida legislator who recently submitted a bill to teach "non-evolution" in schools recently asked "Why do we still have apes if we came from them?" Also, if I descended from my grandparents, how come I still have cousins?