The adventure genre harbours different subgenres and maybe you're simply discovering which type of game you like best? You had no problems with the stand-alone puzzles in Machinarium (not much inventory there) and some of those were pretty hard. I don't mean to steer you away from 3rd-person adventures with lots of dialogue and inventory-based puzzles, but you might give the more Myst-like games a try, for instance
Dark Fall 1 or
Barrow Hill.
Other suggestions:
Return to Mysterious Island. Not hard. You can solve things in different ways, thanks to its inventive inventory system. Play the demo!
Loom is fun and easy.
Gabriel Knight 2 has one or two whacky puzzles, but which game hasn't
and the story is wonderfully immersive.