Was this movie an example of racist thinking in the early '70s? Shouldn't it have been a black athlete that the coach found in Africa? How many white guys are actually running around in the African jungle?
The film makers were obviously looking for a modern day (for 1973) Tarzan character who looked like a 'typical' young Decathlete. Tarzan required a suspension of belief too (always shaved) Note that the newest world's greatest athlete the end of the movie was an Asian/Oriental type. The movie was made for most of the people that would pay to see the movie (young white people), and yeah, it was a little prejudiced not to show the story of a black athlete but today that would be less of a problem.
It was 1973, a black lead would not work on a Disney movie in those days. A somewhat updated version The Air up There with Kevin Bacon (1994) they did have a real African as a co-lead.
Interesting that they did cast an African-American (John Amos) as the coach, who had just about as much, if not more, screen time than Jan-Michael Vincent. So the argument that a black lead would not have worked in the lead role doesn't carry quite as much weight with me. Perhaps they were trying to stick to the "Tarzan" theme too much? That might make more sense why they went with a white lead.
I think the way to look at this is what several people have already pointed out; this is basically a humorous take on a Tarzan movie. You noticed the female lead was called Jane? And the star even says, 'Me Nanu, you Jane".
Incidentally, about a fifth of the inhabitants of Africa are Caucasian, even leaving out South Africans. Look north of the Sahara. It could have been one of them that got lost easily enough; I think Disney went with the missionary thing to make it easier for Nanu to go to his parent's home, the USA
So, we have a white primitive from Africa, a black modern man from the USA and (at the end) a yellow athlete from China, the worlds oldest civilization. The producers of this movie were very obviously not worried about anyone's ethnicity, or linking it to social development, nor should we who view it.
Incidentally, about a fifth of the inhabitants of Africa are Caucasian, even leaving out South Africans.
Black people in Northern Africa were classified as Caucasian because of racism. The "justification" for slavery and segregation was that black people were inferior. Ancient Egyptians and Ethiopians, etc who had civilizations (and credited with creating civilization) were black and this conflicted with the racism at the time. The problem was solved by reclassifying them as Caucasian.
If it was about racism they wouldn't have had black men in the two positions of power in Nanu's life, his godfather and his coach.
The fact of the matter is that Disney made movies to make money (which I don't blame them for) and then, as now, there were more young white people than black people. Some of those young white people would have accepted a young black man in the lead but many would not, particularly in certain parts of the country, and thus Disney would have made less money, probably considerably less.
Disney always tries to mirror the changing times without stretching the boundaries and that's fine because social change isn't their job. Entertainment is.