Yeah it never existed in HD. HD standards weren't even set until the 1990s and weren't implemented until DVD became a thing, and even then most new tv sets weren't HD until late last decade. There are still plenty of flatscreens in homes today that are 1152*768 - technically HD, but shitty, shitty viewing in 32".
Film storage is expensive but paradoxically perhaps less expensive than format-compatible storage over long periods of time for digital-only works, which means some studios transfer their digital to film for long-term storage because they know it will still be viewable in 20 or 30 years time, whereas a digital format might not easily be viewable, and transferring between digital formats might produce unintentional changes within the product.
As a consequence, not every film ever made still has its masters around (big tv shows like Star Trek do, allowing them to remaster the series from scratch - but this is an expensive operation that subsequent remaster sales haven't really justified, which is an example for the entire industry). In the case of He-Man, even if the originals turned up - which is a big if - it was only 2 seasons but it was 130 episodes - that's 22*130 for 2860 minutes or 47:40 hours of footage to remaster, then find buyers for.
Typically, nostalgia-based remakes and re-releases do best about 15-20 years after the original; there are some exceptions (like Wonder Woman, which carried a wave of goodwill to high audience figures for various external reasons), but before that point things tend to be viewed with hostility by the original viewers, and after that point they tend to be viewed with apathy by general audiences.
To take a more direct example, the various G1 Transformers re-releases started about 15 years ago and were roundly criticized for using bad masters. Only the success of the films and other media has kept G1 from falling into obscurity.
It's over for He-Man.