Cornyn not ideal because he's never been a federal judge, therefore is relatively untested.
Our Constitution does not require prior judicial experience or even legal experience to be a member of the Supreme Court.
An Historian could be named and approved since the role is to determine whether laws are in accord with the Constitition and the Founding Fathers meanings, that is the meanings of the thoughts and words at the time of writing.
Legalize is for the undergrads.
A lot of past nominees have not been federal judges.