no matter how many tutorials you watched on how to play a casino game and how to place bet on them it won't take the place of the real thing and when you are doing it yourself, as long as there are free tests and demos for new players there won't be any need to make it look complicated while it's actually not, it's something like other usual games that you play on your phone maybe with some minor differences, most people that want to gamble will try out that game a few times before gambling real money anyway and that really should be more than enough for them learn and know whether they're good at it and want to gamble on it or not.
Also the thrill to try a new game lies in the secret how it works and how much it pays. I mean reading guide is not a bad idea but I would always prefer to make bets directly and try the game maybe with smaller amounts or as you mentioned with free demo.
Most of the games are really simple like dice although the calculation behind is hard to understand but the game itself is really simple, same goes with Plinko, Keno, slots and almost all games. There are a few slightly hard games like Bustabit or as some casinos call it as Blast or Crash because you have to understand when to cashout and what are the limits like how high the rocket can go before it crashes.