If you want DND with working rules, Pathfinder 2e is what people recommend. Not first edition. I’m not a huge fan since it’s still basically DND.

If you want a lightweight system that’s mostly about narrative, I’m a fan of Fate. But Fate is absolutely not a crunchy system, and it’s largely up to the group to agree on what makes sense. Like, if you want character differentiation you can lean on “aspects as permission” and it’s right there. (That is, stuff that’s true about your character permits you to try stuff. The barbarian can’t even try to decipher the runes, because nothing about his character implies he could do that. You can’t just blindly roll something. The wizard can try, because of course wizards know runes)

The core rules are free, but you can find books with more specifics. I think there’s a Dresden files book people like? They don’t provide a complex magic system in the core books, but it has some ideas and the toolkit book has more.

I also liked the chronicles of darkness games, but they’re generally all modern day occult. You can take the core rules and move them to fantasy, if you wanted. It’s pretty light and I like it more than DND in all the ways I care about.