Greeting the Goddess

(This critique might not be the most professional, as I'm a merely a hobbyist myself, but I hope it's worth something nonetheless.)

So, the colors and hues of this are very nice and harmonious - the character looks like it belongs to the scenery and blends in. The story behind the picture fits the painting well, although it's a bit too unsaturated for "evening sun" in my eyes - sunset light tends to be rather vivid, and you did mention the light "coloring" the stone. Example:
forums.steves-digicams.com/att…
While stone is often gray and unsaturated by itself, it still reflects strongly colored light.

Concerning originality: originality is not something I can give very certain critique on here, since I'm not familiar with the full background setting/universe this scene takes place in, but from the surface it does seem rather impressive. I like the addition of the dog skulls, especially. It fits for a festival of death, yet I haven't seen it done that many times, at least in a light as positive as this, but it makes sense as death is a part of life.

But I think the bulk of the critique to be given here is on the technique. While the forms are all recognizable and certainly don't suffer from any kind of "what's even going on here" syndrome which can sometimes manifest in other users' works, I think some things could be improved. This critique ranges from overall issues to smaller details.

This picture seems a bit flat for a few reasons. While the blurrier background, value contrast and the flowers wrapping around the round surface of the stone very nicely do create depth, the range of values is limited (even the darkest color I could find on this still had a value of 55 according to SAI). But perhaps a more pressing issue is the vagueness of the light source, which must still exist, because the evening sun is mentioned. And because it is the evening sun, which is low on the horizon, I'd assume the light is coming from behind the viewer, based on how the light falls on the stone, but the shadows cast by the flowers and the creature contradict this assumption.

The skulls I feel should be less bright (grayscaling the image reveals the skulls to be the brightest objects in the whole picture, which in a way "prioritizes" them over even the character in the foreground) and more shaded. (Grayscaling to check for contrast is very handy, actually, I recommend it for every digital artist who paints.)
A lot in this could be more clearly shaded, actually, namely the creature. The creature does have a nice set of hues, and the markings fit on it, but some of the shades could be deeper. They should have about the same contrast as the shadow of the ear with the neck, or deeper. It's hard to say until experimentation to see what looks best.
Something I can say with more certainty is that the shadow on the ground around the feet should be a lot darker since, coming closer to the feet, less light can reach the ares to illuminate them. The feet don't quite look like they connect with the ground right now. Looking at photo reference can help with figuring out shading like this.

I would have liked to see a bit more detail on the flowers, since the skulls right next to them are themselves very detailed, and therefore make the flowers seem rather amorphous especially when the skulls and flowers are touching each other. The detail doesn't have to be all over the flowers - quite the contrary, actually: only the most profound places (biggest contrast to the background, near focal points) should be detailed, the rest would work well as is, since areas with less focus on them do better with less detail (it drives the attention back to the focal points - based on the blurry background and sharper foreground, you seem to already know a bit about this).

Alternatively, the skulls could have been more soft and less detailed, but the detail given to them here implies that they're rather important, blurring them probably isn't the optimal solution and the previous solution would be a lot more fitting.

Another thing about the flowers: the shades they cast on the stone seem to be the same hue as the rest of the rock. But with objects as vividly colored, I'd say the shades should be more warm because background light reflected from the underside of the petals. It would work to make the flowers look more "there" and interacting with the environment.

On some more positive notes:
I love the way the signature is immersed in the painting. It's so fitting to the rest of the piece that I didn't even notice it at first, but even after noticing it, it doesn't interfere negatively with the painting.
The brushwork in this is good, and the texture and hues of the ground are pleasant and earthy. The composition is harmonious and the image "flows" generally in the right places, even if some of the issues I mentioned before do disrupt it.
The perspective and anatomy on the creature are great. It's a fictional, unfamiliar creature, but it still doesn't look off.

Overall, I suppose this amounts to 3.5 stars. It's not without its flaws, but pleasant to the eyes and tells a story. I know this seemed like a long list of faults, but that's actually a good thing, since being able to point out singular flaws like this means that all the fundamentals are correct, which is much more than can be said of the works of less experienced or more lazy individuals' works.