Of Course "The Legacy" is ERB's "Tarzan", who in the Later Years as Johnny Weissmuller Aged, Morphed into the Less-Physically Demanding "Jungle Jim".
There were Many Weissmuller Tarzan's, the 1st 2 Actually Pre-Code..."Tarzan the Ape Man" (1931) and "Tarzan and His Mate" (1932) that is Considered the Best of All.
But in the 40's Johnny Weissmuller Hung Up His Loin-Cloth for a "Safari Helmet" and "Jungle Jim" was Born.
This Particular Film, for Technical Reasons, is Neither a Weissmuller "Tarzan" Movie or a Weissmuller "Jungle Jim" Movie...it is a Johnny Weissmuller "Johnny Weissmuller" Movie.
An Odd-Duck to be Sure. But that's where the "Oddness" Ends. It's Completely 100% Formulaic of the "Jim" Pics.
Yes, they Did Add a Sci-Fi-ish "Moon Men" in the Title to Ride the "Wave" of the Decades Popularity, but the "Moon Men" of the Title are "Pygmies" and aren't From the Moon.
They are "Slaves" to a High-Egyptian Cave-Dwelling "Sun-Worshiper" (who can't go out into the sun). "She", Oma, is Played by Helen Stanton.
Another Female is On-Hand for some Eye-Candy in the Form of a "Writer" (Jean Byron) who is a Whiz with a Bow and Arrow and seems to Get Certain Glee Shooting Animals and Walking Away.
The 2 Jungle-Babes Make Up for the Lack of "Wild-Life" Footage that is Rather Scant for the Type, although there is Plenty of "Kimba" On-Screen for the Usual Chimp Comedy-Relief.
All in All, it's Rather All been Done-to-Death Before, and it Can't Help but Feel Tired and Dated and has Seen Better Days.
Less Discriminate Viewers and those that have an All-Things-Africa Fetish, with Low-Expectations, might Consider this...
Worth a Watch.