Albert Barnes on Romans 9:24

Even us, etc. See Rom 1:16, 2:10, 3:29,30. To prove that the Gentiles might be called as well as the Jews, was a leading design of the epistle.

Us. Christians, selected from both Jews and Gentiles. This proves that he did not refer to nations primarily, but to individuals chosen out of nations. Two things are established here.

(1.) That the grace of God was not confined to the Jewish people, as they supposed, so that it could be conferred on no others.

(2.) That God was not bound to confer grace on all the descendants of Abraham, as he bestowed it on those selected from the mass, according to his own will, and not of necessity on the mass itself.