I have submitted two stumpers.  We believe they’re by the same author, but don’t remember.  We think the author is also the illustrator, but could be mistaken.  These aren’t quite board books, but little hardback picture books for very young readers.
The first book is about a little prince who wants to play with other people, but he’s considered too special.  In the end he gets to play with the others.  Probably published in the late 1970s or early 1980s.

A remarkable and memorable thing about this book was its illustration.

The graphics were geometrical and simple, almost primitive, and the colors were bold.  The prince had black hair and the main colors in that book were green, red, yellow, black, and white.

My parents bought the books for me at a little bookstore in Elmira, NY, when I was small, probably right around 1980-83.  Would love to find these books for my own boy.  Thanks for any help!