I guess I just don't see it as jabs, Non and Astra have made jabs at Supergirl as well...just a question.
In the last episode, when Non says...
"Astra was wrong, you are as weak as any human" is that a jab, because it is very much like Astra's comment to Kara about Superman.
And as far as the "heir" comment, she IS the legitimate heir to the House of El, she is the oldest.
As far as, let's see, I think another one that has been mentioned before was from Alex. "You are doing more than even Superman"...which she did, WITH THE HELP OF ALEX AND HANK, she defeated a foe that Superman had not defeated, and I have heard from several writers of both Superman and Supergirl that have stated that she is, in fact, in some ways more powerful than Superman, she just doesn't realize her full potential.
So, I don't necessarily see any of this as jabs at Superman per say, but more simple "fact" as far as the "heir" comment, and encouragement as far as Alex's comment.
Just my 2 cents.....