I don't think you understand. If you do somehow manage to roll back to iOS 15, which we've told you isn't supported, you won't get security updates and very soon those who chose to only update to iOS 15.7, will have no choice but to update to iOS 16.
This means if you roll back, as Apple releases security updates to patch some vulnerability, you won't get them. You won't get feature updates at all.
Of all the changes Apple has made over the years with major iOS releases, this to me, is the least major change of them all. It's unfortunate moving notifications from the top of the screen to the bottom of the screen is somehow so unsettling to you, but that's how it is and it's best to get used to it. Or sell your phone and buy something else. But be assured Android and Google also make changes to the User Interface as their devices change and mature.
The day things stop changing, our time on this planet will have stopped.