>>7573672 (OP)The thing is, there's no magic bullet teacher or course that will give you insta gains. You will study many different sources and learn a few new things from each one.
Some material that I recommend for figure drawing and anatomy:
Teacher: Vilppu(the old VHS videos), he was the first instructor that I watch and was game changing for me drawing full body figures.
Book: Hampton, Morpho and Stonehouse anatomy's notes(dense but fun to read).
Course: Proko YouTube, Scott Eaton(best one for anatomy), Will Weston class about proportion and basic anatomy and Marco Bucci YouTube(colour and values)
Also, I learn a lot from many random anatomy notes that I find on Twitter