According to IMDB,com, it was a Japanese animated series back in 1972. One of the voices, Peter Fernandez, still works today. He was a local announcer in the Speed Racer films, and has done directing, writing, and dialog coach. Another, Corinne Orr, was a Grand Prix Female Announcer in the Speed Racer Film.
Jonny Quest seems like it went on forever because there were series that started in 1964, 1986, and 1996. The voice of the 1964 JQ was Tim Matheson, who was in Animal House and more secently in West Wing, Shark, and Burn Notice.
Since you mentioned some super hero type characters, here are a couple of live action super hero sitcoms from way back when:
Captain Nice (1967): starred William Daniels (voice of original KITT in Knight Rider, George Feeny on Boy Meets World, Dr Craig on St Elsewhere) as a chemist in a police department who discovered a liquid which could turn him into Captain Nice, an odd sort of superhero: very shy and dominated by his mother. Captain Nice flew (he feared heights) in his tattered leotards, fighting badguys because his mother told him to do so.
Mr Terrific (also 1967): starred Stephen Strimpell as Stanley Beamish, the weakling proprietor of a Washington gas station, who is also a top-secret super agent. When the Government's Bureau of Special Projects needs Stanley, he takes a pill that gives him an hour's worth of strength, courage and flying time.