first off, i'm absolutely in love with your style; the flatness and shapes convey a very sweet tone. only a few suggestions:
you tried shading the deer, but I don't think you need to. if you want, shade all of them, but with much greater contrast between shades, and conveying the shape of the head more (the deer's shading is just a circle, doesn't show its shape). however, i really like the flat style, because I think it adds volumes to the design of the game.
some frames of your sprites have sloppy borders, especially the first frame of walking right cycle; some other borders, like the first cat's tail in the sideways frames, have sharp right angles, which contract from the otherwise smooth elegance of your characters.
animation wise, only two things stick out. first, your walking animations are very stylistic, and I think they'd work well. however, there's no head bob, so in practice they probably seem wierd (real people go up and down when walking) try adding a head bob on the frame you think the character is lowering her(?)self toward the ground. second, the deer's head doesn't ever turn right when walking right, while all the others do.
as for your screenshot, the house really sticks out because, unlike the rest of your sprites, it lacks a border, has shading, and used saturated colors. all these things detract from the cartoony, sincere style of your characters. the house is also out of perspective (so is the bush): we see part of the roof (like a birds-eye view), but we don't see part of the top of the head of the characters (it's a flat view). choosing a perspective to stick with would give a huge visual unity boost to the game.
all the critiques aside, I love the expressiveness of your characters. the fox, especially, conveyed a wonderful sense of the character through its eyes. I hope to see more!