Others don't have the slightest desire to know what goes on under the skin. If you want to study it in more detail, I have studied anatomy for 10 years and offer a comprehensive course. But you don't need to master it in this great a depth. Just have a general grasp of the details. Practice drawing people of both sexes, all ages, seated, standing, in a variety of positions.
Most artists continue to draw from the figure throughout their lifetimes.
And there isn't an artist alive who ever feels he draws the figure as well as he should. We have learned to block in the figure with jointed cylinders for arms and legs, a thoracic egg and a pelvic block for the torso, a mitten for the hand, and a wedge for the foot. However, there's more to it than that. We must also consider shoulder and hip construction lines from the very beginning of our sketch, for these lines tell us instantly how the figure is standing and how the body weight is distributed. Only when the body is seen standing perfectly erect with the weight distributed equally on both feet, are all the shoulder and hip construction lines parallel to each other.