I still don't see how entropy shows there was greater intelligence in the past.
That's understandable. People of the past saw it.
First of all even if god existed, he would be outside the universe meaning he is not part of the universe, even if he was extremely intelligent intelligent it wouldn't matter because he is not a part of the universe.
A pool shark might be able to tap the cue ball in just the right way so that it hits a second ball which hits a third ball which hits a fourth ball which knocks a designated fifth ball into a designated pocket. But the pool shark can't do this with atoms, or electrons or protons or neutrons.
God does it with countless electrons, countless protons, countless neutrons, countless photons, and every other particle and wave in the universe, to produce complexity, like intelligence and emotion, which come into being in multitudes of people, many years (13-14 billion if you are a standard scientist) after initially tapping these particles into motion. The point? Your puny thinking can't come close to guessing what God can and can't do... if He can be in the universe or outside of it or not.
Our intelligence is by far increasing, I would talk about millions of years ago but you don't believe we have existed for so long so I will just limit to a few thousands of years ago.
Intelligence is complexity. Entropy is breaking complexity/intelligence down. Our intelligence is decreasing. All you have to do is read, for example, Blackstone's Commentaries to see that our intelligence is weaker. Or try Josephus, or any of the ancient scholars.
The difference between people now and then is huge, we are more intelligent mostly because of all the knowledge we have and have access to. In any case our intelligence is definitely not decreasing.
The intelligence you are talking about is not individual intelligence. Rather, it is cumulative intelligence based on recorded findings by many people. Individual intelligence is decreasing.
However, such modern intelligence is destroying the world. At least people of the past were intelligent enough to not join their intelligence like we have, so that they started to destroy the world like we are doing.