I agree with your self-assessment. When I started gesture drawings I noticed my drawings were scribbly too. I think this was happening because I was too focused on the contours of the models. When I start my drawings I try to consider only the necessary lines to convey the pose on the paper, Utilitarian if you will. Look at image 16. You did a great job conveying the back leg with one confident line. Notice how you made a long "S" curve with your line. You could extend that idea and make the whole torso and the back leg with just that line. Practice limiting your marks to the absolutely necessary and I think things will become more clear. :)
I suggest watching videos by steve Huston and Glenn Vilppu for figure drawings. I found these two instructors helpful for me to focus on the feeling of the pose.
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