> However, there's nothing simpler than having a clear D&D rule for something like fall damage, instead of having the party debate if a player survived the fall.

I don't think anyone's suggesting having the party debate things.

D&D has a bunch of precise mechanical rules for combat, and very few for anything else. This makes sense for a game about simulating small-squad combat (which is what D&D started life as), but it's not really what you want for a game about narrative and roleplay. It means combat tends to take up a disproportionate amount of playtime in D&D (because you have all these mechanical rules, and the multiple-round system), when the combat actually isn't such a big part of the narrative or the fun; I've found that most successful/fun D&D groups tend to skip the fiddlier rules (e.g. how many people actually bother with full encumbrance calculations?) and even handwave away entire combats ("you kill the goblins, don't bother rolling").

Think about how you handle conflicts in non-combat parts of the game. If you're trying to persuade the King to overrule the evil chancellor or whatever, how do you do that? You certainly don't have n rounds of following precise calculations and looking up tables about each step of persuasion. Generally you either have narrative steps towards your goal (you break into the chancellor's vaults to collect the papers that prove he's been embezzling, you bribe a reporter to frame him in a compromising position, ...), and/or the GM decides whether your ideas were clever enough to succeed, or maybe the GM assigns a difficulty (modified by the previous two points) and then you do one roll.

In my experience even people who like D&D tend to enjoy sessions where they're doing stuff like that more than doing a series of combats (except for the occasional powergamer type who really does just want to kill as many orcs as possible for 90 minutes - but if you're after "creativity and shared storytelling" then you're presumably not that kind of gamer); often when people look back on a campaign their favourite session was one with no (or very few) combats but one where interesting character moments or story developments happened. (And conversely, more than once I've had a fun session where we were all doing some great roleplay, riffing off each other, and then we hit a big combat and everything just ground to a halt as we had to dig out dice and tables and stop the story for half an hour while we did a bunch of mechanics)

So what if you handled combat the way you handle other conflicts? The GM takes narrative reasons why one side should win or lose, gives the players points for creativity if they come up with a good idea, then comes up with a difficulty and you make one roll. Or maybe you do several rounds of that, but based on the narrative flow of the combat, not just crunching numbers. In my experience that makes for a much more fun, interesting game.

(I actually enjoy, like, Mordenheim or Kill Team, which is the kind of game that D&D originally was. But that's as a competitive game first and roleplaying second. Detailed mechanical simulation makes sense when you're competing about who's better at combat. But it's a waste when you're trying to do collaborative storytelling)