Gerard Williams claims credit for M1 Pro and M1 PRO Max as well:

> Chief Architect for all Apple CPU and SOC development. For CPU, lead the Cyclone, Typhoon, Twister, Hurricane, Monsoon, Vortex, Lightning and Firestorm architecture work. Chief Architect for Apple MAC hardware platform M1 Pro and M1 Max.

I guess they were in the works long before he left.

https://www.linkedin.com/in/gerard-williams-iii-27895aa

M1 isn't a generational leap for Apple. It is just 7% faster for single core than last year's iphone 12. Apple was already so far ahead of the competitors in the chip department for multiple years.

https://browser.geekbench.com/ios-benchmarks

The A15 was released in September with the 2021 iPhone; the M1 was released in November 2020.

A15 was released with the iPhone 13 series this year, after the M1.

Microarchitectures are not developed within a year.