Intuitiveness is a myth. Remember shooters were a tutorial mission explains how to use a mouse klick to shoot and what the health bar means? If you think that is intuitive, why do they have that explanation? Because to someone who never played a shooter even that isn't self-explanatory.
In the previous months I started about a handful games for the first time and in each I had to do some trial and error (a JRPG and an adventure for example) or even reading (Oxygen not included) to understand game and UI. I even remember the first time I played Diablo (years ago) I didn't know what the red and blue bowl meant, but simply playing for a minute showed me.
My point: Intuitiveness is always about recognizing similarities to stuff you know. Red cross is the perfect example. And I bet you never would intuitively know what a blue bar means if you hadn't seen it in some other game before.
It follows that if you have something new in a game, you can make it more or less intuitive by showing where it is similar to stuff you know, but you can never really reach complete intuitiveness. Because there is something there that IS new and that part needs the players brain to understand. By trial and error, tutorial or explanation. Gamers are so used to using trial and error for that nowadays that we do that instinctively and often don't even remember that we did.
If there was no text beside the curved bars you would not know that the yellow bar means armor. Or one blue stamina and the other blue energy.
If it were not explained a player has no chance to intuitively understand a new function unless he saw something similar in another game. He will use trial and error or look it up.