An uncle and an aunt are further classifications of cousin, correct?
No, not at all.
Here is how cousins work.
All black text is from your perspective.
All Red text is from your childs perspective.
All Orange text is from your grandchilds perspective.
For those curious, here is one possible way Derontchis hypothetical Cousin/Aunt could have existed, if they were inbred.
They would be your Aunt because they are your parents sibling's spouse.
They are also your cousin, because they are your parents siblings child, but also the child of the parent of that sibling.
Poll