Willi Stanke und Sein Orchester's "Der Schwarzen Panther"

This morning I listened to the first disc of the compilation Swing Tanzen Verboten!, which is subtitled German Swing, Dance, and Jazz Bands 1937-1944.  The opening of "Der Schwarzen Panther" ("The Black Panther") by Willi Stanke und Sein Orchester sounds a lot like part of "Tiger Rag," specifically the part that corresponds to the lyrics "Hold that tiger," provided it's a version of "Tiger Rag" that has lyrics.  The rhythm of the phrase is the same, and in Willi Stanke's version, it's accompanied by a rapid descending phrase, which is also featured in the Mills Brothers' version of "Tiger Rag" (although theirs isn't as rapid).  This descending phrase is also in Canadian Brass' "Tuba Tiger Rag," which they included in their Tiny Desk Concert for NPR.

The problems with determining whether "Der Schwarzen Panther" is a copy of "Tiger Rag" are that there are so many versions of "Tiger Rag" and that they differ so much.  I have versions by Django Reinhardt, Benny Goodman, Duke Ellington, Les Paul, and - as mentioned - the Mills Brothers, but parts of one version sound totally unrelated to parts of an-other version.

The publication data say that it's a different song.  "Der Schwarzen Panther" is credited to Consiglio and Casirolli, where "Tiger Rag" is credited to LaRocca, Shields, Edwards, Ragas, and Sbarbaro (with lyrics by DaCosta).  However, the musical phrase in "Der Schwarzen Panther" is so similar to that in "Tiger Rag" that I can't believe Consiglio and Casirolli didn't have "Tiger Rag" in mind while writing "Der Schwarzen Panther."  Their title mentions a large feline, too.

It makes me wonder just how different a song has to be to be garnered with a different writing credit.  "Tuba Tiger Rag" is credited to Luther Henderson, yet it's not that different from "Tiger Rag."  By hearing the two, you could tell it's the same song.  Assuming that "Der Schwarzen Panther" is a copy of "Tiger Rag," why are Consiglio and Casirolli given their own credit, where the versions by all of these other artists are credited to the original ensemble?  How different does an arrangement have to be to be considered a separate song?