Hi, Flip. I'm very pleased that you're interested in the inspirations! Hats off!
Don't know what you've seen already but here are some titles to start with:
Movies:
1919 Die Spinnen (Spiders)
1931 Trader Horn
1937 King Solomon's Mines
1939 Gunga Din
1948 Treasure of the Sierra Madre
1953 Plunder of the Sun
1954 Secret of the Incas
1954 King Solomon's Mines
1954 Valley of the Kings!!!!!!!!!!!!!!!!!!!!
1957 Legend of the Lost
1959 Watusi
1973 Trader Horn
+ most pre-1981 Tarzan films
Serials:
1937 Zorro Rides Again
1939 Zorro's Fighting Legion
1941 Jungle Girl
1942 Perils of Nyoka (Nyoka and the Tigermen)
1943 Secret Service in Darkest Africa (Manhunt in the African Jungle)
1944 Tiger Woman (Perils of the Darkest Jungle)
1953 Jungle Drums of Africa
Tonnes more to mention but this is just a basic 'starter' list of the classics. If you have time, take a look at these threads:
Cliffhangers - Republic Pictures & Other Saturday Matinee Serials
Raiders of the Lost Archives: A Shot-by-Shot Comparison
Anyone who has more to add, please do so!