>Is this the first original source musical on Broadway (non-revival) since Urinetown?<
There's also been AVENUE Q, CAROLINE, OR CHANGE, IN MY LIFE, and while it was first developed as a play, I'd also add 25th ANNUAL PUTNAM COUNTY SPELLING BEE to the list. And AVENUE Q, SPELLING BEE and URINETOWN all recouped, so original musicals have fared rather well in this department, of late.
Begin at the beginning and go on till you come to the end: then stop.