There is a difference between what you or others think, and actual facts.
Being from a Sandhurst candidate type background will always advantage careers in the forces. The requirements to get into Sandhurst are rigorous and by nature favor both the privately educated and those from families where public service is an expectation, because it's an officer training academy.
So yes being a royal is likely to give you all the background training to be successful at selection.
I know nothing about the rest but Prince William joined up as Flight Lieutenant William Wales as a co-pilot with the RAF's Search and Rescue force. All trainee pilots start as co-pilots.
In 2012, he was promoted to fully operational search and rescue captain, allowing him to command missions which he is known to have done well at.
He then served as a full-time pilot with the East Anglian Air Ambulance, again initially as a co-pilot while he got his civilian certification to fly hefty Sea Kings.
Again standard for a transferring pilot The biggest difference between him and any other pilot is he rightly donated his earned salary back to the NHS.
The man was a proper co-pilot in training, and then a proper helicopter pilot, not some sort of 'dummy' role because he happened to be next in line.
Your emphasis and assumptions are simply wrong.
Don't let your dislike of what family he got born into blight your relationship with the truth of his capabilities as a helicopter pilot.