Hi paps, there is no such thing as 'normal'.

Every child is different, and none of them are 'abnormal'.

If your son prefers YBCR now, then go with that for now! If later he prefers physical cards, then go with that! Just follow your child's lead. We often hear from parents how their children's preferences change from time to time. The most important thing is to not force it and keep lessons joyful.
One other tip you could try with LR is to make lessons personal for him. Eg., use your own pictures - ie., pictures he recognizes from his own life (eg., when teaching parts of the body, use pictures of his own or your own body parts!). Even videos! And you could focus more on the Categories which he likes.