The original show was just meant to be a fun way to pass the time
Well, that's rather dismissive of a show that frequently told stories that confronted fraught and controversial social issues such as racism, sexism, rape, Vietnam, the Kennedy assassination, etc. For its day, it was quite intelligent. Indeed, it was one of the shows (along with
Star Trek: The Next Generation and
Alien Nation) that ushered in a new era of smart, sophisticated science fiction TV in the late '80s and into the '90s, raising the bar considerably from the general schlockiness of the '70s and '80s (with only rare, isolated islands of quality like the
Twilight Zone revival,
Starman, and
Max Headroom).
It's true that QL was a fantasy show whose scientific premise was absolute nonsense, but just because science was not a priority does not mean the show was insubstantial in other respects. It was actually pretty powerful and meaningful for its day, using genre storytelling for social commentary the same way Trek and
Alien Nation did. (Although it did badly bungle its attempt to tackle homosexuality, requiring the
Quantum Leap tie-in comic to do a story by author/gay activist Andy Mangels that brought back the rather vilified lesbian character from the episode and portrayed her in a more nuanced light.)
so obviously they never really elaborated on the moral implications of what they did, but if I remember correctly Sam could only leap when he made things "go right" that in the original timeline had gone wrong. So the implication is that in the Quantum Leap universe there is a universal concept of "good" and "evil" independent of human morality
"To put right what once went wrong" isn't necessarily about good vs. evil. That's
doing right or wrong.
Going right or wrong is more about successful vs. unsuccessful outcomes, happy vs. unhappy endings. Sam's missions were more about helping to fix individuals' lives, to help them succeed when they failed before. Sometimes that was about correcting an injustice or saving a life, but it could be as simple as helping them pass an important test, or get their act together so they could succeed at achieving their dream or fixing a broken relationship. Sam was doing good, but in the tangible, everyday sense of helping make people's lives better, not some cosmic battle against reified evil.
The whole thing that the producers embraced to differentiate QL from other time travel shows was that it wasn't about big cosmic matters of good and evil or important historical events like Pearl Harbor or the Moon landing or whatever (the Kennedy episode being a rare exception). It was more the kind of show that was common in classic TV before the modern age of serialization: an ongoing series that works like an anthology, with a format that's basically just an excuse to put a continuing lead character or characters into completely different roles and situations every week, so that you get the narrative flexibility of an anthology combined with the convenience and audience appeal of a regular cast. The time travel and leaping into bodies were just an excuse to do historical dramas focusing on various people from all walks of life, while having a single lead actor to play all those various people.
Come to think of it, that's a cause for concern about the sequel series. Most everything these days has to have some big mystery or conspiracy arc revolving around the main characters, and any case-of-the-week plots are just there to reflect or advance whatever's going on in the big arc. And that's the opposite of the spirit of the original show, where the situations of the week and the people Sam became were the important part, with Project Quantum Leap itself and the effort to get Sam home just being a background element, no different from Richard Kimble's hunt for the One-Armed Man. I wonder if the show will be willing and able to recapture that original focus on historical dramas about the everyday lives of diverse people, rather than making the whole thing about the Project and the mystery and the guy doing the leaping. The fact that there's a whole ensemble cast of Project members suggests it may be largely the latter.