AWWW these are wonderful and let me get more specific as to why,
-bold lines- i'm such a sketch myself i wished i drew strong like you more often, and what did you even do with that bike-scene, there's something with it that makes it actually feel downhill, what a cool thing! >w< and the others are also such cuties,
if you feel there's something missing in your work, or that you aren't satisfied, sometime you can look at your favourite artists and ask yourself "how are they doing this". But you want to keep the questions very small and specific. Say you find a drawing where the character has a really hecking awesome shaded eye. Then you can think about what it is that makes it so, and see if you can come up with a rule for it and apply it to other things. Like, absorb and mix and apply x)