This is pretty much the take you get right outta american high school: full of propaganda. This is extremely simplified, ignores mass amounts of genocide and slavery, and ignores historical events to compare it to. The development of america as a nation is built on the corpses of hundreds of millions of africans, chinese and native americans which notably were stripped of their 'right' to private property so that someone else's 'right' to private property could exist.

You do not in any way need to enslave people in order to develop land; only to develop land AND enrich a bourgeois class of people.