However, that is not an infallible document.
The teaching of Humani generis that Adam and Eve were real individuals is indeed an infallible expression of the ordinary and universal magisterium.
For a RC that is, based upon your judgment that that it is what was always taught everywhere, or as Rome defines always and everywhere. That the stories in Genesis were always held as being literal would be harder. However, i was addressing the premise that since something is taught in an encyclical then it is RC infallible, which it is not.
They do not understand that most of what they believe is anything but infallible !!
God bless.