I think you did a great job and specifically the legs on the left most figure and arms on the right most figure show the realistic muscles of human anatomy. I think you could up those curves even more. It may be helpful to look for references with very muscular people to learn about how the muscles interact. I find that those curves and slopes are what provide more energy behind a pose. Great job for your very first lesson!
I think you are getting a general sense of proportions and it's good you're dividing the limbs and the body in sections.
Despite that I think your drawing seem a little two dimensionals and they lack the illusion of 3D.
To show that you can either draw solid shapes for the main masses of the body (chest, pelvis) or build a line hierarchy to show what is in the foreground and what is in the back.
I love it and it is so good for your first gesture practice! Maybe try to break up the body into organic shapes rather than lines connecting around the basic points. I found that really helped me to get a less 2d feel at the start. I think you did amazing and I love the use of the points and lines! Maybe try drawing basic shape lessons those helped me a lot with figure drawing.