And I'm not sure what the transperancy does, care to inform me?
This image of Youmu is in PNG format and has transparency. With transparency, it shows what's behind the image instead of having a black or white square behind the image. Most image editing programs let you know let you know your image has transparency if you see a checkered board behind it.
This next image is JPG which does not support transparency, you can see that there is a black square around Youmu. You can also see that Youmu's colors are outside the outline, this can be because of 2 things, that area is semi-transparent in the originial image to make some sort of an aura effect or it can be that it was painted in that area and the eraser was used.
If you still have your image in the format with the layers seperated, try saving it in PNG and upload it again.