I have found that regardless of the TTRPG, the game lives or dies by how good the GM is and indeed overly complex rules just get in the way of the game rather than enhance it. For example rather than having the players roll some dice against a characteristic to solve a puzzle why not give them a physical one you made yourself and have them use their IRL skills instead?

It is the same with combat. Fighting should be part of the adventure but if it just becomes an escalation of dice rolling, where is the fun? If I wanted to just chuck a load of dice and cards at someone I would play Warhammer 40k. A good GM will add a narrative bend to fights or again have enemies that can only be killed with some creative solutions.

I base all my games on the tried-and-tested Heroquest game system which offers almost laughably simple combat mechanics, no XP levelling but in doing so makes itself a lot more flexible to creative input.