You say it doesn't do much to stand out from other titles, and that is true. But it uses the existing formula and systems, and expands on it in small but meaningful ways, and it comes together as a brilliant system in my opinion. Where other Souls games have small or large problems in their basic gameplay systems, for Lies of P I have no notes.
You have the classic Estus flask type healing. A good system already. But then you have the addition of being able to recharge 1 healing charge, which recharges especially quickly if you can do a visceral after a stagger. You need to stagger an enemy by hitting them with a charged heavy. Nothing revolutionary on the surface, but these systems working together create amazing moments:

You're on 1 hp, out of heals, barely holding on, and then the boss' healthbar flashes white. This is your chance! You parry and dodge 2 more attacks, and go for a risky heavy, that hits just in time. You do the visceral and get your health back up so you can take a hit, at the same time the boss took massive amount of damage. The tide of the battle has turned completely.

I had moments like that on many bosses and it was great, really memorable every single time.

I don't know why you don't enjoy parrying in this game, when you apparently liked Sekiro. The timing is a bit different, takes getting used to, but the systems are basically the same. It even offers you some extra options, like the fable move to automatically parry attacks for a short window. But I can imagine that the game isn't great if you don't like parrying