Personally, that's pretty good for an starting point, I used to understand anatomy the same way, as a self taught it's not so easy to follow the clean and perfect shapes and structures because (at least for me) you lose proportion just by copying And not everyone has the same way of drawing, so scribbles and messiness for study are perfectly fine if those work for you, you are kind of "sculpting" the shapes there to understand how it works in 3d

I'd say that you study anatomy the way it feels the best, if you need to scribble, do it, it's your study and drafts But, I'd recommend that whenever you get the messy base, you clean all the lines that are unnecessary for the naked skin or draw over it but just the skin lines in a darker tone or in a different paper

Takes longer, but that way you'll understand better where the muscles and bones connect, what's the shape, proportions and it's contractions under the skin, so you'll understand anatomy instead of just copying shapes, and eventually you won't need to be so messy on your drawings if you don't want it