If they'd called it "Space Jam 2.0" it'd almost be appropriate: "New Legacy" is the same basic premise, but with improvements everywhere.
And maybe a little TRON rubbed in for good measure.
I literally saw the original Space Jam earlier this year for the first time, so I don't place it on a pedestal. There's no nostalgia tint for me, outside of basic pop culture references to it.
I liked the original, but overall it felt like a flick of certain era, who's success was largely boosted thanks to the obvious gimmick involved.
New Legacy, too, is a gimmick film, make no mistake. But in 2021, nothing it does technically, as far as modern audiences are concerned, is "special". Mixing humans and CGI and classic cartoon animation is old hat by now, and no longer a feat that can carry a film to success, alone.
While New Legacy absolutely pushes as hard as it can into the marketing cross-over spectacle, and the real life/animation gimmick, the actual skeleton of the story that's draped over is much stronger. It now leans hard to the relationship between a father and son. In fact, it's central to the conflict both at home, and on the court.
Don't misread me: it's still corny as hell, and you have to kind of go in with a certain attitude and accept that it'll be absurd. But that's no more or less than what you needed to enjoy the original film.
But overall? I dug it quite a bit. Wasn't expecting that.