Actually Biden only vowed to select a
woman as his running mate. As for qualifications to quote Biden on the topic: "“The most important thing is that there has to be someone who, the day after they’re picked, is prepared to be president of the United States of America if something happened,”
Biden's vetting committee (Lisa Blunt Rochester, Chris Dodd, Eric Garcetti, and Cynthia Hogan) vetted eight potential running mates for Biden including Senator Harris but also
Michigan Governor Gretchen Whitmar,
UN Ambassador Susan Rice,
Sen Elizabeth Warren of Massachusetts.
Wisconsin Sen. Tammy Baldwin,
Illinois Sen. Tammy Duckworth.
New Mexico Gov. Michelle Lujan Grisham
and Janet Napolitano director of homeland security
Only 2 of the 8 candidates were African American showing your claims about a black woman being first and foremost criteria to be just wrong.