A freshly minted pilot has the best handling skills he'll ever have? Hahaha, a truly laughable opinion. But it's what keeps the internet so interesting.
The few really natural pilots learn skills quickly. But they can't compare to the experience of guys with more experience. And yes, skills decline with age.
The top fighter guys typically have several years existence before they really mature. The best guys in my old squadron were in their late 30's to early 40's. Double turn? They're get tired when I was a young buck flying against them. Triple turn? They're toast.
Skills fade. Computing speed fades. Ability to handle G's fades. But the dkine is MUCH slower vs the learning curve young guys have to climb.
See many young test pilots? Surgeons? Leading academics? Coaches? Quarterbacks? Aerobatic pilots? Youth has tremendous positve attributes but there are certain fields where experience and additional education take time, which means the peak level is older.