I like the clean style!
her head is way too big though

water/waterfalls look great! maybe a bit of foam/splash would make them even nicer?
the apples are an interesting choice. but I think the hearts are so universal, they would
not stand out as shameless copies.
On the waterfalls, I am overall trying to keep a good balance of detail vs. minimalism, for example if one thing gets too detailed then a lot of other stuff looks too plain by comparison. But maybe I'll try adding some particles for the spray and see how it feels.
I like the apples! Both the apple icons on the left and the map icon on the right are way too close to the edges of the screen tho IMO. You should make the horizontal margin a bit bigger so that the icons don't lick the edges. It looks like the image has been cropped a bit.
Don't worry, the screenshot is just the contents of the HTML canvas, when you play the game for real it's surrounded by a larger black background, so there is plenty of space around it.
Will you make the editor available to people to make their own campaigns? Kind of like
Zelda Classic except less awful?
Releasing the editor is a very strong possibility. The editor already works well enough for what it does. I might need to modify the map format to be more compact, and then come up with a good way for people to share quests and an easy way to play custom quests that others have shared. The nicest way for this to work is a central server where the editor uploads new quests and the game can browse the server and download the quests you want to play. The crappiest way is that you zip the whole game with the new quest file and people download it, unzip it, and open the webpage from their filesystem.
Also, Zelda Classic is one of the reasons I started this game project. I downloaded it a few years ago, started messing around making a new quest for it, and then realized I might as well try making my own zelda clone, and here I am.