It's not 2 protagonists, check the scorecard.
Yip. Iran 1 US 0.
For the regime merely to survive was going to be a win, they achieved that and, from the initial proposed agreement, much, much more.
You're confusing the size of someone's hammer as an indication of ability and success, but it is only one tool with limited effectiveness beyond destruction of infrastructure, not of will. Infrastructure can be rebuilt, and from the sound of things, there is still no shortage of missiles and drones, nor the ability to produce them.
The Iranians have a much smaller toolbox but it is filled with a wider variety of tools which they still retain, along with the desire to use it and the same network of willing allies.
They absolutely are a serious protagonist in the region, if they weren't there would be no conflict.
Military action is no more likely to stop extremism than it could stop stupidity.
It absolutely will not stop the domestic nutters who will drive their cars into crowds or build pressure cooker bombs for public events, something that this action has guaranteed by recruiting new generations of martyrs for the cause.
We have learned all these lessons before, but at least all the defence companies are in for serious dividends for the foreseeable future.