You’re just describing transformative use. I’m not a lawyer, but an example from music - taking a single drum hit from a james brown song is apparently not transformative. Taking a vibe from another song is also maybe not transformative, e.g. robin thicke and pharrell’s “blurred lines” was found to legally take the “feel” from Marvin Gaye’s “Got to Give it Up”

Which is all to say that the law is actually really bad at determining what is right and wrong, and our moral compasses should not defer to the law. Unfortunately, moral compasses are often skewed by money - like how normal compassess are skewed by magnets