People used to ridicule Iran when they introduced Shafagh and Saegeh fighter jets; however, with the development of Kowsar, with its digital display, new avionics, radars, and the engines that take it to a fourth-generation level, I don't think the statement that "
Iran is not in a position to build fighter jets plain and simple" can stand up to scrutiny. They're already building fighter jets, and while they are not in a position to challenge major fighter jets producers, their announcements and documentaries clearly show an indigenous fighter jet program.
The Kowsar may look like an F-5, but if everything else is different; and with the exception of airframe, I doubt the Kowsar can be considered an F-5 fighter jet.
Through trial and practice, it allows the Iranian engineers to develop the next successor to Kowsar. And if anything can be learned from the Chinese model, persistence pays off. Thirty years ago, people used to make fun of Chinese planes. Well, look at them today.