"I’m having down difficulty distinguishing between pelvic floor and vaginal wall, and also higher up – cervix and womb, etc. Am I supposed to be able to feel these all as separate entities?"
This is very common for women around the world, as sometimes the muscle-to-mind connection isn't there. However, over time you can feel them all!
You can use the triangular hand position where your thumbs connect together at your navel and your index fingers connect below your navel to make a triangle over your lower belly. Right where your pinkies fall naturally is over your ovaries. Your pelvic floor is what you would squeeze to stop urine from flowing.
You can find your vaginal walls by inserting a finger into your vagina and finding what you would squeeze in order to squeeze your finger. You can find your cervix by putting your finger up your vagina and the womb is right above that.
It will all come in time with familiarity!