Mahomes is great, there can be no question.
However, can you think of a better situation for a talented, young QB to fall into? A head coach who is arguably the greatest offensive mind of his generation. A veteran QB who entered the league with high expectations (Alex Smith) to draw upon and sit behind to watch. It was the absolute best possible situation for him to fall into and allow his natural talent to grow.
Mahomes is the John Elway of his generation, but with better early support and success.