I know this question is a little trite but where do you get the inspirations for your designs for the ominous island?
Its not trite at all, you are essentially asking how to be creative, which is a taught rather than innate skill that requires deliberate cultivation.
Creativity is a form of problem solving born out of limitations. You need to be able to recognize what your limitations are, then consider your options for integrating them into your solution (consider the classic example of a coin being used in absence of a screwdriver). There are a number of limitations we are all working within when creating things in the game: low resolution textures, limited options for features, placement barriers. There are also common limitations you see players impose upon themselves though they aren't explicitly limitations that the game places on the player, like wanting a character to look acceptable at every angle and in every expressive animation.
A common limitation I've seen others mention is their inability to draw, but I've seen this this easily sidestepped with stamps and tracing. And I will mention that even skilled draughtsmen feel frustrated if they are used to dealing with particularly high resolution images due to their perceived lack of control over the smoothness of their drawing. This is a pixel based application and requires both an eye for simplification and the patience for meticulous cleaning of details (using the joycons and not a stylus) in order to be legible at the resolutions displayed in-game. So the ability to draw in itself is not something that effortlessly produces what the creator desires. Anecdotally, many pixel artists I've known can't "draw", their process is closer to cross-stitching, perler beading, or even building in Minecraft.
Outside of all of that you are in a sandbox where you are allowed to create essentially anything at all. There is no real guidance in the form of island items or game progression. Once again, creatively it is more akin to Minecraft than it is to Animal Crossing or The Sims -- you are literally in control of all the creation that happens within the specific "biome" of the island. This can lead to a lot of choice paralysis and aimlessness if you don't begin setting your own limitations to work around.
These limitations don't have to be draconian. A simple limitation is picking one feature from the mii maker and then building around it until you have something interesting. Personally, I utilize the island layout and object maker to impose thematic limitations, building up the island itself as a character and then creating miis that could live within it.
















