What is a good thesis?

I have this thesis for my English essay:

In the short story "The Story Of An Hour" by Kate Chopin and the poem "A Work Of Artifice" by Marge Piercy, the women are restrained, overpowed, and ruled to become socially "adequate".

I asked a girl who is majoring in English Literature and she told me this is not a thesis, this is not like an argument, this is like an statement.

I have trouble to distinguish a statement and an argument.

I understand a thesis is like "Apple is good for you because of A, B, and C" and an statement is like "A is good". (Am I right on this?)

But when it comes to the supports, when it comes to write about A, B, and C, I don't see the difference between a statement and a argument.

And help would be greatly appreciated!

Thanks for your time!