I like the fluid shapes you have going here, particularly the first 2min drawing. Be careful though, if you go too fluid with every section of the body, it might make it end up looking like they are made of rubber. As an exercise in dynamicism I think it's good though.
I would just like to mention this general art tip: straights & curves. Google it for more information; I haven't studied it enough yet, but it might be helpful for making your art dynamic and giving more emphasis.
Have to tell you that most, if not all artists, will most likely be unsatisfied with their drawings. Everyone is constantly improving - if you don't find issue with your work, you might stagnate. Try looking at older drawings to see how you have improved to feel better about where you are.
It might benefit you to try and speed up your drawing process - the 1 minutes are somewhat bare. If it interests you, practice without the "line of action" spine and balls for joints so you can spend more time focusing on the overall shape.
I will say that in your 10 min drawing, the hands/feet/head are very lacking in detail. The shading attempt looks interesting though.
If you have concerns about drawing 3d shapes, I recommend drawabox. Never before did I realize that I can't even draw a flipping cube before trying to use that site. It will help with construction of 3d forms.
By the way, I like your attention to muscle groups/shapes in the drawings.
