> Ordinary American citizens didn't like the idea of being colonizers, since they had, not long ago, been a colony themselves and fought to free themselves.

Bad comparison: the American Revolution was a group of colonialists rebelling against their colonialist bosses, not a rebellion of the colonised against the coloniser. Indeed, one of the American Revolution’s complaints was that London was too protective of Native American rights, and was limiting its colonies expansion into Native American territories. So rather than an anti-colonialist rebellion, it was a pro-colonialist rebellion