The F-18 and F-15 prototypes were competing for the same job. F-15 won and MD managed to salvage their investment and sell the YF-17 to the Navy as the F-18.
The F-16 was the card up Boyd's sleeve that nobody saw coming but couldn't argue against it once he put it on the table!
The F/A-18 was never in competition with the F-15 WRT the Air Force. It was mandated by congress for the navy to replace the high cost f-14 with something more reasonable costwise. It's true that the F/A-18 was competing with a navalized version of the F-15 but cost factors and the lack of organic multirole made the navalized version of the F-15 unfeasible.
The F-16 did not conform to what Boyd wanted out of a combat aircraft, execpt for the lightweight part. The F-16 has a RADAR, BVR, and while designed as an air superiority it has exceeded expectations as a multirole platform.
No, the F-17 and the F-16 were both part of the LWF (Lightweight Fighter) project. When the F-16 beat out the F-17, the USN decided to pursue the F-17 which became the F-18.
The F-16 was the card up Boyd's sleeve that nobody saw coming but couldn't argue against it once he put it on the table!