The aesthetics feel great, and the multiple layers of mountain gives a good depth of the arena. The dinosaur sprite is very cute, and the color palette made it look almost 3D. I think it looks great, especially if played on a phone.
Some design problems:
You chose very bright colors for the background and the objects, a lot of the things meld into the scenery and it isn't pleasing to look at. I would recommend a different color set, check the 'color wheel' on google and choose opposing colors for backgrounds and game object
The dinosaur moves too slow in contrast with its size. A more appropriate movespeed would be 5x ~ 7x its width per second.
Objects spawn too close to each other. A minimum distance of 0.5x each object's width is recommended.
Other than that, I'm looking forward to checking out that source code. I have no idea you coded this, I think it'd be great to learn.
Happy Pixel Day!