Charlie Brown does feel more like a symbol of a bygone era rather than an embodiment of the 21st century American psyche

Yes, a time when children entertained themselves outside interacting with other children, and adults were so peripheral to their lives that they could be portrayed always off screen by a mumbling voice.

Yeah. I remember thinking it was old and boring as a kid in the 90's... Have children born after the millennium even ever seen a newspaper, let alone read the comics?