I saw this comparison on Reddit and found it interesting. The original post stated that the He-Man theme was just a sped up version of the Remington Steele theme. There are threads scattered throughout online about who ripped who off. One of the level-headed threads pointed out that Remington Steele switched to this theme in 1982. He-Man also debuted in 1982, so it is highly unlikely that one ripped off the other.
The Remington Steele theme was recorded by the great Henry Mancini, while the He-Man theme was recorded by Shuki Levy. I had hoped to find a common composer. I’m assuming though that the similarity was caused by some similar outside inspiration. Is it a conspiracy? Did one composer/company rip off the other one? I’ll leave that for you to decide. In the interim compare the He-Man theme above with the Remington Steele theme below and make your own decision.