You could always move the canopy up a bit to show more of the branches, and have more holes in it. Baobabs aren't usually this lush.
I think the lack of depth comes from a couple of factors:
1. They appear to be shaded like they're in side view rather than from above. From above, with how flat the leaves are, we shouldn't see so much shadow on the bottom. Also remember that baobab leaves clumps are rather flat. The tops of them being shaded creates a very round, bulbous look, which isn't very baobab-like.
2. They're shaded independently of one another, there is no sense of some being lower than others. Think about the tree in 3D space. Which clumps block the light from reaching other clumps? Why is light able to hit all the branches even though there are leaves above them? Since with this combination of view, light source, and leaf clump shapes, you can't really rely on the clumps to create depth, you need to use overlapping and cast shadows to create depth.