Cren Avola

Who is she?

From what she says she is a Hylian and Rito hybrid. Born into a wealthy family in a land across a ocean. She travels as a student of magics new and old.

What is said above is true, but as usual there's always more. 

Birthed by a mother who had fell in love with a rito. The mother's family didn't approve of the relationship. Fairly normal childhood with other town children poking at her about her rito traits. In  school she shown the ability to excel in using magic. (Depending on headcanon)Later she left home to collect an item from a sky spirit to gift her the ability of flight. From there she left home to travel the vast sea to learn of more magics old and new.

In my own headcanon, hybrids can contain many or a couple of features depending on genetics. In example: Cren has the arm wings and legs of a Rito and the colored hair and non-feathered body of a Hylian.(some have headcanons of ritos having feathers on their body aside from the arms) While one could end up with the beak nose, white hair, and body feathers while having plain arms and legs.

In summary, it's all about genetics of the parents of the hybrid of what traits the offspring might end up with.