There is a highly observable chasm between animals and humans. Animals can do what we can't and vice versa. The main one is language and absence of innate behavior in humans.
Using one's own inner experience as the rule is solipsism. It basically denies the world around you. I can see why personal fancy can play a dominant role in such an approach.
“Using one’s own inner experience as the rule is solipsism.”
Wrong. You do it every day. It is an inescapable part of life.