Going solo early says far more about your age, your training frequency, your quality of instruction, your local airfield and the attitudes of your school and instructor than it says about your ability to learn fast.
And even then, an ability to learn quickly, is not a measure of your ulitmate capacity. Einstien didn't learn to speak until he was 3.
Ok,let's take an example.Let's asume that we've got 2 guys starting their training at the same time.One is working hard every day,from early in the morning till late in the evening,waking up with the books and going to bed with them.When the weather permits he's flying listening very attentively to his instructor,always analizing mistakes he makes,trying to improve.He knows everything about the airplane he flies and when the weather is bad,he's just sitting in the cockpit on the ground,studying the checklists,simulating the flight.
Then we've the second fellow.He's not stupid and he dreams of becoming a pilot aswell.But he's studying only what he has to,doesn't ask any questions,he's trying to fly well,but when the flight is over he's rushing back home or to the pub,then he forgets about it very fast.He's not thinking about his training when he's on the ground.
So who do you think will go solo earlier?