We won't know whether or not we're intelligent until we meet another intelligence: and can begin to make comparisons.
Can a creature alone be intelligent? She can use the word certainly: but how valuable is the meaning?
Same with any monotheistic god. Thor can run into Mars, Diana into Venus. They can begin to assess each other.
A self-described as intelligent man could run into a self-described as intelligent God. That could start something: if we actually ran into each other: not words, not stories buried in jars. (Unless we found out that his self-description was actually our description, palmed onto him. Then we'd just be back with self again.)
Until we have n intelligences, or n gods, all fighting it out, we have nothing more than a bushbaby masturbating on a tree limb.