@bob-crum I'm interested in learning about the qualities of different expressions as well, but I haven't looked into it much yet.
You might want to look up Paul Ekman, a psychologist "who is a pioneer in the study of emotions and their relation to facial expressions." (Wikipedia) He's well known due to the TV show "Lie to Me". He's written several books, including "Unmasking the Face: A Guide to Recognizing Emotions from Facial Clues" (with Wallace V. Friesen)
Amazon: https://smile.amazon.com/Unmasking-Face-Recognizing-Emotions-Expressions/dp/1883536367/ref=tmm_pap_swatch_0?_encoding=UTF8&qid=1530585983&sr=8-1

From the reviews I've read, it's more of a reference book or textbook, rather than reading for entertainment, but it describes the facial expressions of basic emotions including the muscles used for different expressions.

Paul Ekman and Wallace Friesen's work has a lot to do with people trying to hide their emotions (whether consciously or subconsciously), but most people can't stop a tiny flash of the emotion on their face or in a gesture of the body. And the facial expressions look the same during these miro-expressions as expressions that are displayed openly. They also found that basic expressions are universal around the world.

Paul Ekman also has training programs to learn how to read microexpressions.
Paul Ekman Group: https://www.paulekman.com/

I agree that #2 clearly shows Wren's swift escape. I like how the poses are based on the animals.

@tessaw I like A & D the best (B seems like it could be read as angry instead of exasperated). All the additions look good! I also like the simplicity of the first one at the start of this thread. Whatever you decide to go with, this piece makes a fun little story!

@carriecopa Here are some photos that might help with ideas:

@judy-elizabeth-wilson This one looks like gift wrapping paper.

@lenwen I saw the final in the Contest post. The added detail & golden colors in the shell really changed the focus of the image to your characters. You did a great job!

@carriecopa Straight lines draw attention, so maybe you could try an arched bridge to soften it up a little? It could either be a structured bridge arching up, or a simpler bridge (like a rope bridge) that hangs down more in the middle.

I'm not good with perspective, but I think the fox is tilted a little more towards the viewer than the rest of the image. See how you can see more of the side of the vehicles in these photos?

I like your sketches & the fun whimsical feel.

I'm happy you decided to post. It's fun to see everyone's work, no matter what level it is--plus, it's great to see people improve! I don't think you need to worry about that anyway, since your sketch is just as good as many of the others posted here. I'm a beginner, too, and have seen my work improve from help here on the forums. I hope you are able to work on this some more. I'm interested to see more of it!

@TessaW Good point on exploring a concept with different thumbnails. I know I need to work on this, too!

@artbytra I agree with the other comments.

I was wondering why the traveler stopped there and why the bag is on the ground. I think having it slipping out of the hand or sliding off of the arm would convey the idea of it being dropped better. Also, it looks like they stopped at the mushroom, rather than being overwhelmed by the village. I think a crouching position would be confusing.

I'm not really getting the breaking down element--for example, there's a door built into the mushroom top on the right--so it looks like the mushroom was in that position when they decided to build a house in it. If the village is broken down, the structural elements should be breaking down along with the mushrooms. Another way to show that it's old could be to have faded colors and cracking / crumbling edges. I believe this happens to some real mushrooms as they age.

Another little thing--the steps aren't cut to the same scale as the ladders and doors of the village.

Tree on the right feels awkward to me--like someone chopped the top off. It could be nice to have branches hanging down, but it isn't balanced with the rest of the tree.
Here are some photos that can give you some ideas:

It's a nice concept, and I'm looking forward to seeing you work on it!

@holleywilliamson I'm really liking #2 as well, especially the mother frog & Thumbelina. I think the tree feels super thin & tall, and is taking up more attention than it deserves -- maybe because it's the only straight lines, and it comes down forcefully through the middle. It might not have as much effect once it's rendered if it has rougher texture to soften the straight lines and if it blends with the background.
I love S curves, too! If you do want to change it up, you could try moving the mother frog & Thumbelina into the lower left corner & have the frog son in the upper right--creating a simple curve instead of the S-shape.
I also like #4. Maybe you could add to the excitement by giving some movement to her hair and dress.
These are a great start! I'll be watching to see which one you choose!