Americans were pretty much divided at the time of the War of Independence. Maybe a third sided with the Crown, another third supported independence, and the rest probably didn't care either way. Following independence, a smaller number of Crown loyalists (between 60,000 and 70,000 people) moved to other parts of the British Empire, chiefly Canada and the Caribbean. Ultimately independence was successful because the British government lost domestic political support in the British parliament and foreign powers that were opposed to Great Britain such as France and Spain sided with the insurgents and intervened in the war.
African-Americans and native Americans didn't have a say in the process either as they were not citizens, which the original Enumeration Clause in the US Constitition BTW makes patently clear. In the case of native Americans in particular, one of the stated goals of the insurgence, as mentioned in the Declaration of Independence, was to promote settlement in the Indian territories to the West of the original 13 colonies, which was opposed by the British government at the time. Incidentally, although the grievances in the Declaration of Independence are directed at King George III, most of them were actually with the British Parliament or the British government, rather than the King personally.
