Was Charlie Brown unlucky? I don’t think so. He had lots of friends who cared about him (Linus, Schroeder,Pig-Pen, Peppermint Patty, Marcie, and more). He had a wonderful dog!
To the extent that Charlie Brown represented Charles Schulz’s id, Schulz battled depression for much of his life. And yes, he did describe that in an interview:
“Schulz admitted in interviews that, like Charlie Brown, he had often felt shy and withdrawn in his life. In an interview with Charlie Rose in May 1997, Schulz observed, “I suppose there’s a melancholy feeling in a lot of cartoonists, because cartooning, like all other humor, comes from bad things happening.”