I think yours is a pretty common experience considering that Witcher 3 was a huge mass-market success and Witcher 1 was a niche product made both by and for insane people. I say this as a shameless Witcher 1 apologist.
I almost regret how long it put me off 3
They could have redone it as a Carmen San Diego style dialog game and it would have been better than the turd they shipped. It's really quite bad.
The Witcher 1 combat is secretly not bad. It looks like an action game though and the game does a terrible job explaining why this is wrong. So it feels absolutely horrible. You have to understand it's more of a rhythm game. It's closer to Assassin's creed or Batman combat systems. There's a lot happening on screen but you are mostly waiting for the right moment and choosing tactics.
The story carried Witcher 1. Gameplay was vastly improved in 2 and I have mixed feelings about 3, the game was definitely more successful and I think you can partially attribute that to changes that made it easier to play and thus much more console friendly.
I for one welcome a UE5 remake of Witcher 1 and will purchase it for sure, if only for nostalgia sake.
W2 made alchemy useless cause potions lasted like 3 minutes and cut-scenes were included in that time (so you take a 3 minute potion, enter a 2 minute cut-scene and your potion stops working 1 minute into the boss fight). And W3 made potions less of a hassle by auto-refill but streamlined this too much - you could refill anywhere so you always had potions so resource management wasn't required. And the secondary ingredients and side effects were gone so the system is much simpler.
Also the tactical aspect of combat was ok in W1 - adjusting the fighting style and sword combination to the enemies. It just wasn't an action-RPG despite the action-RPG interface. It would be better served by turn-based combat.