Would you say any of these famous songs are Jewish? -- "The Way You Look Tonight," "All The Things You Are," "Smoke Gets In Your Eyes," "I Won't Dance," "The Last Time I Saw Paris." What about "Old Man River," as sung by Paul Robeson? Like so many of the most popular songs of the middle of the 20th century, Jerome Kern's music seems to define an American idiom. Some people go so far as to say the only really successful non-Jewish composer of the era was Cole Porter. All the explanations I've seen for this phenomenon seemed rather circular to me. But what American (secular Jew or any other stripe) could fail to love this music? Not me.
Maybe this is only a story: Jerome Kern and Oscar Hammerstein considered creating a musical based on the life of Marco Polo. Hammerstein said to Kern, “Here is a story laid in China about an Italian and told by Irishman. What kind of music are you going to write?” Kern replied, “It’ll be good Jewish music.”
For more on Jews in popular American music see "Jews & Musical Theatre: Jews hand a hand in writing nearly all the great musicals of the 1930s and '40s" and "Songs of Songs: What are the 100 greatest Jewish songs ever?"