Nick is the blob at the bottom of the tree that is helping another up the tree. This is because throughout the book, he is always helping everyone achieve their goals, but stays at the bottom of the food chain nonetheless. The expression on this blob closely matches Nick's perceived mood in the story. He is always seen and perceived as a joyous character, full of curiousity and excitement for what's to come in the escapades of Gatsby and others.
Jay Gatsby resonates most with the blob in the top-right of the tree. He is alone at the top of the food chain. Rich and powerful, yet he acts like he has nothing and is completely alone. This blob is seen sitting down, far away from everyone else, not offering anyone else to be with him. He is the type of person who believes that he would be more likeable if he portrays himself as an outcast, and that people (such as Daisy) will go out of their way to want to be with him. I believe that this is his tree, and he is popular in the same way someone is popular when they have a trampoline or a new video game. The grumpy expression depicts his hoping the one person he wants to see isn't catching the hints he is laying out.
Myrtle and Tom are the two blobs close to the middle of the tree, hugging. They find great joy in the company of each other, even though others are aware of their cheating, particularly George Wilson. They are hugging one another, showing that they are affectionate toward one another.
George Wilson is the blob to the right of the two hugging. In the tree he is seen angrily staring at Tom and Myrtle being affectionate toward one another. During the novel, George is just mistreated by these two, and the blob depicts that in a figurative way, as he is sitting relatively close to the two of them yet he is excluded, both physically and from the truth of the matter. His wife runs away with not a care in the world for indefinite amounts of time, leaving him blind to the truth of the matter, which is that Tom, the true antagonist of this novel, is breaking hearts left and right, and not a single blob sees it coming.
Daisy is the blob at the bottom of the tree being lifted up by Nick. While her face cannot be seen in the depiction, one can infer that she is having a good time alongside Nick. She is slowly climbing the tree, gaining insight along the way. The reason I picked to put her in this viewpoint is because Nick was the main person guiding her toward her inevitable destination of meeting with Gatsby.
I picked to put Jordan in the center of the tree, as she is in the center of every plot point, yet her character and her blob both share the quality of having everything to do with nothing and nothing to do with everything. She is happily amidst every important plot point but still manages to not play a significant role in any of it.