All rational creatures created by God are either men or angels. Catholic tradition recognizes no third category of rational beings.
Sacred Scripture teaches as fact that only eight human persons survived the Flood, as stated in Genesis chapter seven verse twenty three and in First Peter chapter three verse twenty. Since this is explicitly revealed by God in Scripture and unanimously upheld by the Fathers, it cannot be questioned by any Catholic.
You're absolutely right about what it says in the Bible. But to play devil's advocate here, those eight people survived
on earth to repopulate the earth. The Bible is silent on anyone surviving
off the earth. Our Catholic faith is based on the Bible AND tradition.
How do we then account for the centuries old legends of the native peoples?
I think I'd be more comfortable with people
leaving earth than non humans
coming to earth as I personally don't believe God created any intelligent beings other than angels and humans.