Ah, good for you for experimenting with your own style, that's an excellent way to grow as an artist. I normally would not critique style experimentations since those are more personal growth things, but I will give my thoughts on the matter. Messiness can certainly be charming, and in fact it often is. That is what makes pencil sketches so endearing to many artists. The Kirby Luma certainly did stand out with the way it was shaded; I actually rather like it. The only thing I would say is that I think you may have been so caught in the shading that you sort of lost some of the shape, namely the forehead. I think you put a few too many shading lines on the forehead, which compromised somewhat the round appearance that the creature should have displayed.
I will say though the shading lines themselves are pretty neat, as the lines do follow the shape and contours of the luma. A few of the others though, namely the Ghini and Tektite on the first page, the lines don't seem to follow an overall coherent structure, which distracts from the shape of the creatures. So by all means, continue to tweak and experiment, because those are the main steps on the road to improvement and growth :>