I notice that during the legendary on-the-spot broadcast (and resulting newsreel) of the Hindenburg disaster in 1937 features the exclamation from the broadcaster "Oh, the humanity!". Is this the first notable use of this phrase. Can this instance be considered the origin of the phrase in popular use?
Yes, the origin of the phrase "Oh, the humanity" was introduced into popular culture by WLS Chicago announcer Herbert Morrison as he was describing the Hindenburg disaster while watching it unfold.
Morrison's description has been dubbed onto the newsreel film of the crash, giving the impression of a modern television-style broadcast. However, at the time, newsreels were separately narrated in a studio and Morrison's words were not heard in theaters.
Morrison coined the phrase "Oh, the humanity." This phrase is now commonplace in popular culture.