Basically, you do need cards to have fun. I’m sure everyone will l trip over themselves to tell you it’s f2p and it is if you do dailies everyday, all the boss battles and general grinding you can amass a collection (there’s also guantlet, but you know about that). You’ll definitely need luck tho as getting cards you want with the disenchant rates are unjust (but I come from a card game with a market and so disenchanting to me is super mega inefficient). But if you want to try many of different cards and decks and as f2p, this is a long dream.
As far as gameplay goes, I generally enjoy duelyst anyway. There’s a steep learning curve that misses people where you have to stop playing your hand out and start reading your opponent, and once you’ve here cards start making less of a difference and its more about skill, but again I feel this is more for a competitive experience as opposed to an explosive one. I saw a steam just today of a guy in bronze running a fault deck who should have lost but ultimately won as his opponent was a beginner. This will frustrate you at first, but I think it’s quickly overcome with research and practice.
As far as Guantlet goes, you shouldn’t start there, it isn’t beginner friendly. While the upper tiers of the game may be very meta centric, in bronze, silver and gold you may run into those kinds of decks, but whatever deck you have generally can compete because good decks don’t just win you the game. I was told you really shouldn’t get into guantlet until you’ve reached gold on ladder.