I hope they paid well for the license. I wish they would give credit to the artists by name. I originally found (and acquired) these on craftpix, then came across them on cartoonsmart and discovered your name. As far as pixel art icons go, yours stand out in style and being complete. I really want to use them just having trouble deciding on characters and environments that fit the style the best.
Thank you, I'm glad you liked the icons :)
Regarding the style of characters and environments, I would recommend a minimalist style with outline. For greater consistency, you can recolor all the graphics under one palette. I think it would be easier to recolor the icons.
I hope my answer helped you. Just in case, here is the palette I use: