This game creator is pretty simple, but still has alot of potential. The different elements are fairly simple, yet I can imagine that you can create harder puzzles/rooms with it, however it might be a problem for larger puzzles that rooms reset after you enter 2 different rooms afterwards.
Your sample level also shows all features of your creator in a very good way without being too long, hard or boring.
However I do have some problems to note: I know that this game creator isn't really designed to be on a webpage (as the sharing of the levels requires going in the game's files and copying and pasting folders) , but having to scroll in a flash game is not really a good choice, as the whole page scrolls when you scroll when you are not in full screen, so maybe if you want to actually improve the webpage version I'd reccommend rebinding the keys for scrolling through your items to prevent the entire page from scrolling.
Also I noticed that you can place multiple instances of the player on the map, which lets the game glitch out a bit when 2 or more instances of the player are in different rooms. you should limit the player count to 1, or, when you intend on implementing a feature where you can switch between different player instances, make it like that so that the camera focuses on only one instance of the player and only controls on the selected instance.