If you’re a wokester, you probably think American imperialism started when the English colonists landed at Jamestown in 1607. I don’t agree. The initial efforts at colonization were generated by private actors, and the notion of ruling over vastly numerically superior Native Americans at that time would have seemed ludicrous. The objective at that point was to find adequate land to develop without antagonizing the natives too much.
By about 1650, however, things had changed. European governments were taking more of an interest in the colonies. The Navigation Act was passed, thereby establishing a mother country/colony economic relationship that would continue for over a century. The European colonies were starting to bump into each other. The colonists were no longer grossly outnumbered by the natives. An era of imperialism, albeit one in which the interests of private actors still predominated over those of governments, had begun.