]This is both serious and satire. She is serious in saying that if novels are to be recognised as being worthy, then their very authors must stick up for them like she is doing.
In Belinda, one of the very novels JA mentions in her Defense of the Novel, the author Maria Edgeworth begins the book with this advertisement:
Every author has a right to give what appellation he may think proper to his works. The public have also a right to accept or refuse the classification that is presented.
The following work is offered to the public as a Moral Tale—the author not wishing to acknowledge a Novel. Were all novels like those of madame de Crousaz, Mrs. Inchbald, miss Burney, or Dr. Moore, she would adopt the name of novel with delight: But so much folly, errour, and vice are disseminated in books classed under this denomination, that it is hoped the with to assume another title will be attributed to feelings that are laudable, and not fastidious.
I think JA is making direct reference to that.
Also in Belinda, one of the characters Lady Delacour says "You are thinking that you are like Camilla, and I like Mrs. Mitten—novel reading, as I dare say you have been told by your governess, as I was told by mine, and she by hers, I suppose—novel reading for young ladies is the most dangerous—"
And the 'Camilla' to whom she refers is the title character in another book JA mentions in her defense of the novel.
In Camilla there are passages like the following.
Having read no novels, her [Eugenia, a character} imagination had never been awakened to scenes of this kind; and what she had gathered upon such subjects in the poetry and history she had studied with Dr. Orkborne, had only impressed her fancy in proportion as love bore the character of heroism, and the lover that of an hero. Though highly therefore romantic, her romance was not the common adoption of a circulating library: it was simply that of elevated sentiments, formed by animated credulity playing upon youthful inexperience.
It's interesting that the very books that JA praises in her Defense of the Novel appear to be guilty of the offense she criticizes!