Hallo Ivan,
I fear you cannot ask this question of the people in which you refer and expect to get an answer - Americans will not know what 'Americaness' is - it is an outside perception. It would be an opinion, based on what you see. So, how do you as a Russian, preceive Americans? I have lived here for many years with Americans and each one of them would have a different opinion of themselves and America. So, you would need to generalize (bring together) all of the things you see as American. It is what you, Ivan, feels that it is.
Regards,
CF