Intelligence is usually understood as a relatively fixed factor that cannot be trained effectively. Algorithm design is mostly about the patterns you already know.
IME how many patterns you were able to rote-memorize is a very small factor in how good you are at algorithm design; the limiting factor is more likely to be your ability to filter out irrelevant details and abstract out the essence of the problem and see how that relates your library of patterns, and that part is mostly innate rather than trainable.
But you're claiming this is somehow not "intelligence"?