It is certainly correct to state that the US fly-boy's didn't have the "practical" experience prior to the war, small exception US pilots serving in the RAF or the ROC (Flying Tigers).
But this Luftwaffe "experience" is still an extremely overrated topic in WW2 literature.
The amount of Luftwaffe fighter pilots that had served in the Spanish Civil war (like my father) wasn't really significant - and they had losses too, but tactical experience was brought in by those pilots to their home-units in Germany. Supposedly the 4 finger formation (Schwarm) broken down into two wings (Rotte) was developed by the Luftwaffe during their tour of Spain.
However the RAF had already developed the same basic principle on their own and started to make use of it during the Luftwaffe attacks onto the Lowlands and France.
Radar had even enabled the RAF to develop tactics involving very large formations - which the Luftwaffe only managed to achieve by the mid of 1942.
However without a doubt the nation with the most elaborate-extensive flight training already before the war, was the USA. And this really stared to pay off once the USA entered the war.
The average US rookie before the war had 250 training flight hours under his belt - before even being transferred into an active unit, gaining a further 50-100 flying hours.
The Luftwaffe (Generation of the Aces, or Battle of Britain) had 200h in average - there are very few Luftwaffe pilots like my father who had 350h+ before the war broke out.
Due to Hitler constantly using the Luftwaffe as his main "intimidation" force during 1936-39 towards the Brits and French in regards to the Rhineland occupation, annexation of Austria and Sudetenland - almost all basic flight schools were working at half capacity, the advanced flight schools at 30-50% and the fighter schools were almost entirely out of operation from 1937 to 1939 - the remains of Jagdfliegerschule Schleissheim (only 1 of two in existence) was down to a single squadron.
As such the advanced flying school and fighter-school experience could only be obtained at the respective active wings - and a lot of brown-nosing was required to get that additional experience. Off these approx. 2000 Luftwaffe fighter-pilots with what the Luftwaffe considered to be the best (in regards to training hours and Spain experience) - around 60% lost their lives during the Lowland/France and BoB. What came after that had approximately 100-120h of combined flight training. from 1943 this figure dropped to 60-80h and from end of 1944 it was around 30-40h. 1945 onward most of these boys could even get their aircraft of the ground.
Germany's top ace Hartmann, received his basic fight training at the school lead at the time by my uncle. He wasn't even considered to be a good pilot. By the time he reached his front-unit, minus the private hours he had obtained due to his mother and glider school - his total flight-hours comprised of less the 120h. IIRC he and his mates even busted a bunch of Ju-87's that they were supposed to transfer to the front. He was one of those very few who "enjoyed" and "survived" rigorous advanced flight training at his active unit for more then 6! month.
The Luftwaffe's advantage in the first year of the war - was the element of surprise attacks (Blitzkrieg) that accounted for more then 70% of enemy aircraft destroyed on the ground. Similar results were obtained in the first 6 month upon attacking the SU. Actually exactly as to what later the Luftwaffe faced in regards to Allied superiority in numbers
with most of the Luftwaffe assets being destroyed on the ground.
The US aircraft also are constantly underrated in the common literature. Germany's supposedly best fighter-aircraft the Fw-190 was in vast majority allocated towards ground attack wings and not fighter-wings. So the Luftwaffe's main fighter component was made up of Bf-109's and their variants.
The Americans had the P-38, P-39, F4f and the P-40 - all four basically more or less on par with the Bf-109 - and an even better aspect towards versatility. Even the P-36A was accredited with downing two A6M2 Zero's during the Pearl-harbor attack. Now add an average of 250 training flight-hours on top of that - and the best prepared air-force in 1940-1941 was already that of the USA. Put on top the production output of aircraft and training output of pilots from Jan 1943 onward plus the new aircraft types as the P-47, P-51, F4U-4 and F6f - impossible to match for any other air-force.
I can't quite follow onto your perception of the Luftwaffe wing-man - just having a lookout. He was totally integrated by the leader so as to take advantage if the leader overshot, missed the target, failed towards total distruction or the opponent out-maneuvering the leader. (flight curve interception). it was not uncommon for the wing-man to actually make the kill once a dogfight ensued.
However many Luftwaffe pilots with, "sore throats" (eager for a Knights Cross) claimed their respective wing-man's contribution, couldn't care less about their wing-mans safety, or even ordered their wing-man to stay out of their target pursue.
There is a reason why amongst the surviving long time Luftwaffe pilots - those NAZI propagated/chosen Aces, later Allied literature propagated aces - were in majority disliked - even hated. Galland, Wick, Gollob, Marseille and v. Werra - were some of the most prominent characters amongst those kind of pilots during the BoB.
Germany had lost the war on the ground, on the sea and in the air the moment the US started to supply the UK and the SU prior to even the USA entering the war themselves.