Im class c (1400-1500) and yet I know basic openings such as London or the Caro, I also know basic tactics such as skewers, pins, and zugzwang. I can also sacrifice material for basic tactics like skewers. However, my main weakness are endgames. Especially when both sides have equal material. You made a small error in your post by being too generous and giving players a higher elo than they deserve. But who cares, it's simplified anyways. You dont have every point of view
hope one day i can reach 2000