Final answer:
According to Zinn, Native Americans, enslaved Africans, and poor whites were not enthusiastic about the revolution.
Step-by-step explanation:
According to Howard Zinn, the three groups that were not enthusiastic about the revolution were Native Americans, enslaved Africans, and poor whites. During the American Revolution, Native Americans faced ongoing conflicts and dispossession of their land by the colonists. Enslaved Africans saw limited opportunities for gaining freedom and often faced harsh conditions. Poor whites had their own grievances, such as economic inequalities and resentment towards the wealthy merchants and gentry.