Was Rockwell taking inspiration from the illustrators and painters of Europe? Of course his "Rosie the Riveter" very consciously quotes Michelangelo.
Left: Alphonse Mucha, 1906, Beatitudes/Blessed are the Persecuted. Right: Rockwell, 1926, Defeated Suitor
But I wonder if he was looking at other, less well-known sources. We may never know for sure about those examples. But if he was looking, more power to him! He'd be crazy not to take inspiration from the greats of his recent past.
Left: drawing by Ernest Meissonier (from book by Gréard, 1897), Middle: Rockwell, Ichabod Crane, 1937. Far right: Rockwell, Tavern Sign. [Thanks, Morgan for that last one]
I put the microscope on my own work in the post "Borrowing"