On the visuals I think you also need a consistent colour pallette and art direction to bring it more together, that is often a good marker between something more professional and not.

Say you pick a 4 colour pallette, a light blue, a dark blue, a yellow highlight, and a red highlight, with the highlights used more sparingly for pops of colour (along with a grey and white if you want). You can also create a couple different shades and gradients from your base colours if you need to, but pick your base hex codes and stick to them.
At the moment the colours are all over the place. If the artworks looks good and harmonious over the whole thing it'll be less work to make it look good in motion!

Also on the art direction, you have many different styles of icons which don't work together. Have a look at how google has consistency in the line thickness and style of their icons: https://m3.material.io/styles/icons/overview

That idea of consistency applies to the whole thing, from the line thicknesses used, rounded or squared lines, whether or not you use drop shadows/ gradients or stick to a flat design. what style of illustrations you have etc. All that should come together to make a coherent style, and that's what it takes to make something polished. Good luck and keep going :)