You did a good job of keeping the body and your lines simple. You have good line confidence in the torso.
Having a general concept of anatomy can help improve form and deciding where to place your pen/pencil. Drawing a circle for the head is a good start, but think about why you are drawing the circle. Where is that shape in contrast to the rest of the skull? Is it the back of the head? Is it the starting point for the face? Maybe think of the circle as an anchor for the rest of the head that it will connect to. If you can't visualize it, try starting small by breaking down the skull into basic/general shapes. You can then apply that mentality to other body parts.
Your first drawing (on the left) did a good job of showing the person's left/front leg in perspective by giving it an oval-like shape that forms off of the bottom of the person's torso. Also in that same drawing, I can see you used foreshortening to position the other leg. This is a good technique to use for any part of the body in perspective, however it may be best to focus on anatomy before applying a "style" that usually invents itself with the exaggeration of perspective.
My last comment is the have more confidence in your lines. In the right-most drawing, the legs show a lot of "chicken scratch" lines. Try to commit to the line by planning where to put down your pencil, and thinking about where you want your line to end up before you move the pencil. You are off to a great start, stay curious and keep at it!
These are great gesture drawings. My only suggestion is that it might be helpful to draw where the joints are (in the shoulders, elbows, knees, etc.). Unless the intention is that you are going for a cartoon-ish/"rubberhose" style in these gestures, it's still very helpful to be aware of the anatomy the character is based on so you know which proportions and poses to push.
Regarding the anatomy, it's important to "anchor down" where specific body parts are. I would otherwise recommend drawing boxes for the palms and ankle bones, and then extending out the lines for the fingers and feet respectively from there. But for the sake of gesture, keeping the shapes simple is great for keeping the "flow."
Specifically in the second set of drawings (6), the arms tend to start lower than the shoulder because the joint and shoulder/deltoid muscles aren't shown. Find where the joints would go, and then base the gesture off your understanding of anatomy. Raise the shoulders, lift the elbows higher, etc. Knowing where the body parts would go can only strengthen the impact of the gesture.
