Nice work there! Unfortunately I don't have the patience to give criticism to each and every one of them, I'll try to come up with a general statement.

While they are quite good on a technical level (nice shading, anatomy et cetera) they seem kinda cliche. Especially the first one seems like a poster for a very bad and trite shonen anime. Though there are some nice renditions of stick anims and characters. Though my favourite is the fourth one. It has a surreal charm and it makes it more interesting than the other stickart. Also I don't see a reason for the second picture to be there since it's clearly inferior to the other ones.

Yo is that Avenger as a stickman?

In any case, it's not too shabby. I drew a lot of stickmen myself back in the days. Your lines are quite messy at times so I'd suggest you try and make lineart on top of your sketch, because it's easier to color and it comes out neater.

Keep working, drawing, studying. :)