According to Wikipedia:

Leadership

Chair: Jaime Harrison, former Chairman of the South Carolina Democratic Party[11]

Executive Director: Sam Cornale, former Chief of Staff of the Democratic National Committee[12]

Deputy Executive Director: Roger Lau, former Campaign Manager for Elizabeth Warren for President[13]

Political Director: Alana Mounce, former Executive Director of the Nevada State Democratic Party

Chief of Staff: Anatole Jenkins, former National Organizing Director for Kamala Harris For The People

Vice Chair of Civic Engagement and Voter Participation: Keisha Lance Bottoms[11]

Vice Chairs:

Gretchen Whitmer, Governor of Michigan[11]

Tammy Duckworth, U.S. Senator from Illinois[11]

Ken Martin, Chair of the Minnesota Democratic-Farmer-Labor Party[11]

Vacant

Treasurer: Virginia McGregor[11]

Secretary: Jason Rae[14]

Finance Chair: Chris Korge[15]

In addition, a National Advisory Board exists for purposes of fundraising and advising the executive. The present chair is Elizabeth Frawley Bagley, former U.S. Ambassador to Portugal.

https://en.wikipedia.org/wiki/Democratic_National_Committee

They are going all in for Biden because Biden wants to run. He is the head of the Democratic Party so everyone is afraid to say no to him. Initially, the DNC didn't want Biden to run, but he was insistent and they caved.