I like your illustration, I think it is very strong. I also feel your frustration around social media, I've had similar thoughts, it can be feel very good when your images are liked and shared and can boost confidence etc. all of this is good, but should be treated as an added bonus. I've been in the situation where I like a piece I make and post it and then the interaction it gets determines how I feel about the piece. I found this to be problematic because social media was dictating my confidence. And the reasons for it getting little interaction could vary so much and most of which have nothing to do with the actual artwork.
Some points I have on your image are:
The top of the umbrellas which are facing up towards the sun could be lighter as a result of being hit by the sun, and the inside of the umbrellas could be warmer and lighter, If you look at a photo of and umbrella in the sun, it is almost translucent when light goes through it, I think that is referred to as sub-surface scattering.
I think possibly the underside/belly of the turtle could be a little lighter as it is going to get some reflected light from the ground in the shadow. Possibly overall the shadows are too dark, I would keep the darkest shadows for the areas where no light can get in.
I think the textures describing the surfaces are lovely, the rabbit or hare's colour is possibly too similar to the shell.
I do think the characters are great, nice expressions, nice concept.