Yes, indeed the British army was far more superior to the American army in the early war. The British forces were of course more superior to that of the American because they had had a well established system of government that had the backing of its government back home. In addition Britain, since the 1700’s, had practiced a system of Mercantilism and one of the major principles of his system of trade was maintaining a strong army for the purpose of conquering new territories which would as markets for their raw materials and also the source of cheap raw materials and cheap labor.
On the other hand America was at a disadvantage as they were outnumbered and out maneuvered. The American population was only 2.5 million in which 20% were African slaves. The Native Americans were also united against the Americans.
The British managed to maintain superiority over the Americans because they were well trained and organized and had the backing of their motherland.
Americans were able to sustain the rebellion when they attacked Washington on a period that Britain had a break. In the winter of 1777, with the help of the Prussian the continental army had been well organized and trained and proved a formidable opponent by cutting off the British of their supplies in Canada. It also gained new allies who financed the much needed supplies.
General Washington’s tactics of delay and decisive attacks while keeping light also enabled the Americans to be swifter in their attacks. The militia created by Washington was least reliable as a fighting force it did a fantastic job at containing loyalists.