Does this not depend on how you define football intelligence.
Broadly it would be processing information quickly and making good decisions based on this information.
But every action a player does on a pitch involves some level of decision making.
Initially what I think of as demonstration of football intelligence is your traditional number 10.
This player operates in the most congested area of the pitch. Typically they will have to process position and movement of 4 defenders, plus opposition midfielders, 6 to 8 of his team mates, and the football itself. How all of these variables interact with each other, with him and with the goal. It is a huge amount of constantly changing information, if you tried to model it you would need a super-computer.
The best exponents of this position take in all this data, make a quick decision and have technique to execute this correctly. Then they repeat that, over and over. They recognize flaws, mismatches, gaps in defense, they have 360 awareness of awareness and make passes that others don't even see.
I am coming around to accepting there is another form, which probably requires more on processing speed and but there are fewer variables. This is probably closer to what people call talent/skill. It is what Messi and the great dribblers have. They can recognise tiny subtle changes when opponent is off balance /wrong footed and instantaneously beat them with simple touches. AWB has this in form for reacting to opponents and getting in tackles.
I would say AWB is lacking in the first form of intelligence above, partially due to inexperience. He does get caught out of position and makes some poor decisions when there are more choices to pick from. But when he has limited choices like in a one on one, he is excellent. Rashford is probably another in this category.
Mata probably is one of our best in the first type. Greenwood looks really promising, I have been so impressed with his decision making, especially for his age. I think Lingard is quite decent in this aspect, his movement intelligence is good, but his execution or technique lets him down a bit.
Our lack of true intelligent attacking players is probably one reason we struggle against packed defenses. But in counter attacks, when it is about speed of thought and speed of action we excel.