Other than the number ticket or the bucket which would probably have a purpose in the full release, every other item you mention serves a purpose as another route/path.
The candle is part of a route as a way to skip finding the keys and doing that dark forest area and the valves is way to drain the water instead of having to solve the elevator problem. There are also several other item that have uses too, the only exception are the ticket, the bucket, and the fish.
Assuming that the fireplace puzzle is difficult for you, I doubt that you will understand how to do the potion route and most likely missed the majority of characters in the forest.
Plus, other than the several chases in the game, I don't see any of the mini-games being that difficult and that it's probably the device you're playing on is slow or that it's just you.
Either way, if this is considered to be a hard game for you, then you haven't played many horror RPG games.