Probably literally meant people from the US. In English, standard usage assumes "America" to mean "USA", and references to the region are referred to as "the Americas" (plural), with the north/central/south regions being considered largely separate. There's very little value in referencing the majority of the residents of the western hemisphere as "Americans", as there's really nothing they have in common beyond that.

There is more than a little tongue-in-cheekedness about this document. The fact that it's a humourous slight against Americans (that is, citizens and residents of the United States of America) doesn't mean it isn't true.

More importantly, it's making the point that all communications are fraught with lack of clarity and misunderstanding.

As this very subthread is evidence.