I agree with you, that inheritance isn't all of OOP, but I think it is one of THE unique selling point of OOP. All the other things like abstraction, interface

I agree with you, that inheritance isn't all of OOP, but I think it is one of THE unique selling point of OOP. All the other things like abstraction, interfaces, encapsulation, polymorphy, etc. all exist(ed) before and without OOP.