Our group finds that combat takes too long, and part of this is down to HP grinding. At first we thought it might be due to too many dice rolls, but that's not the problem; the problem is that our ability to keep immersive descriptions going is hampered by the turn-based CRPG feeling of chipping away at hitpoints without much to say about it (there's only so many times you can describe stabbing a troll in the arm because anything else would imply that you're doing more damage than you actually are according to the HP).
However, we still want a chance for failure and PC death so that our successes feel earned, so how can HP be removed and yet some sense of challenge and balance be retained? How can we describe our fights based more on creativity and the descriptions of those ideas but without insta-killing everything? If anyone has any experience with using this optional rule for reducing the role of HP used during combat, I would appreciate their answer to this question.
So my question is: How can combat retain the challenge and balance that playing RAW (i.e. tracking HP and damage rolls) achieves without using HP (or at least reducing its importance)?
For context, we've decided that combat takes ages and isn't fun for us, especially if you have an enemy with a large number of hitpoints or large numbers of enemies. We're not that good at describing combat because we're just chipping away at those hitpoints and it's hard for us to keep up flavourful descriptions when we're not really doing anything significant; it feels like a turn-based CRPG. We are interested in the narrative, more so than the challenge but we don't want to just turn it into a story where we just describe how we win everything; we still want it to be a game, with a chance of failure and where our successes feel earned.
We've decided that we want to turn combat into purely description based scenes, lead by creativity rather than numbers (i.e. we can defeat things by being smart about it and what makes narrative sense), playing loose with RAW (for example, using Thorn Whip to swing across a hole that a pursuing enemy might fall in, not something that RAW would allow because it says you have to target a creature), but then released that there's no way to decide that we might fail.
So then we considered turning all combat dice rolls into essentially ability checks, where you simply describe your idea and roll something to see if it works (i.e. you want to shoot a troll's leg to make him stumble, not something that can happen RAW since there's no body part targeting, so as an ability check the ranger would roll "d20 + proficiency + DEX mod + whatever" to hit a DC that the DM thinks reflects the difficulty of the task; not quite the same as rolling vs. AC because it's specific for the situation and the task you're attempting rather than the creature's context-less ability to defend itself).
The trouble with this is that we don't know how we'll judge damage and potentially PC death with this light usage of the dice/rules/numbers, although that might simply be something we'll figure out as we go, but hence my question, does anyone have any experience playing in this way?
Note that this isn't a criticism of 5e's RAW, it just doesn't have the right feel for the game we're trying to play at the moment (with another group I'd be happy to play a strictly RAW game). Also note that despite the fact that D&D might not be the best fit for the kind of game we want to play, there are things that D&D offers that we like and would prefer to modify how we play it so that we have the best of both worlds, as opposed to picking a different game/system (we do have other games we can play instead, so we know that's an option, but we still wanna make D&D work for us).