Yep, they are Terraria traces.
In the .kra directory. Might need to show hidden files if you on a *nix.
Not to mention the "Free" in the title.
Why do you have a watermark on the preview?
You cannot host non-commercial works here. Non-commercial is not considered open.
It'd be nice is the tags drop-down list only would only show good examples of tags (or give good tags priority). Ideally from an officially curated list.
As it is, it is flooded with the worst malformed tags which doesn't help matters any.
eg. trying to add a pixel art tag, an official pixel art tag should be first, should it be "pixelart", "pixel art", or "Pixel Art"?
The image also contains a Pokeball, the design of which should be subject to copyright and which I imagine could also be a trademark.
Most artists are familiar with "competitions" as a scamy way for unscrupulous types to try to get art for little or no cost ("If you enter your art we'll use it in our game!"). Doing such will likely have the opposite of the desired effect.
If you are really looking for talent, find artists with promising portfolio's and offer them paid art tests.