this is just what ive thought. im not a professional of some sort but this is just based on my experience. Shape manipulation is hard, especially when you wanted a fast results. You need to start from the very beginning, which is drawing shape. from what i see from you, you need to learn how to draw the shapes first.
the thing with shape manipulation is that you need to have a lot of references, unless you can create it by yourself. As a beginner, one of the way is for you to actually trace the reference photo.
for example, this is how i do it. i trace the photo to get the base of the pose rather than created it myself. pls note i dont use shape that much, because my style of drawing doesnt require me to use this.

Tbh in my eyes, your top drawing has more fluidity when it comes to movement rather than the bottom. The bottom one kinda looks a little stiff. It would be better if you twist the body a little bit because you draw the jaw in a certain angle.
thats why i really recommend beginners to:
1) practice by tracing
2) practice by drawing fanart of certain animes or games that you like
3) learn the basic things like drawing eyes, hair, etc.
4) use 3d model pose apps or assets (this helps a lot saving time in webtoon creation)
5) Learn and find references for outfits (for your characters to look more interesting)
6) optional: I learn drawing by starting to draw chibis, you can try it
This is a process of me drawing a fanart straight from the 3d model asset. (I didnt do a proper lineart cuz this is just for fun)

All in all, if you want to try drawing using shapes, you can do so, since it will helps you create a more complicated art in the future. Shapes helps a lot in drawing action poses, animals and even background.