I love how you made them life like with all most no detail. That is talent.
That is something I am trying to figure out over time. With that style of drawing getting the pose and the feel is more important than the details. Knowing what to leave out is difficult.
I think it was Jeff Watts in one of his videos that said a lot of people try to draw every little bump or muscle, etc. and wind up making someone that looks like the Michelin man.
An artist has to sort out what is a key detail, and what is just making it too busy. I tend towards just drawing what I see, and sometimes trying to get every nuance I get my proportions way off, and make it too busy.
But what he suggests (apart from holding your pencil underhand, making long smooth lines, etc. all of which I don't do), is drawing quickly, short sketches from life (or reference if that is what you have), and learn to make quick decisions as to proportions, what to include, etc. He places a lot of emphasis on anatomy studies as well, so you know what you are looking at.
He also said that doing master studies help you to see through the eyes of accomplished artists to see what they include, and what they do not.
I do some anatomy study, but I tend to go more toward the camp that draws what it sees on the outside, without always knowing all the details underneath. That makes it harder to construct figures without reference, however, and you can sometimes indicate lines that don't match the underlying structures, which causes issues. So I think everyone needs some anatomy study if they want to draw people. It is a major time investment to learn all of the muscles, bones, structures, etc.