The structure and meaning of "that's all there is to it"

[Sweetpumpkin]

Hi,

While watching the drama 'Persuasion'(BBC, 1995), I saw Anne Elliot says this: And that is all there is to it.

In the drama, she is presented with her family to some ladies in a higher rank(the Darrymples). Then she shares the experience with her cousin, Mr. Elliot, saying:

But I can discern no superiority of manner, accomplishment, or understanding in the Dalrymples. And that is all there is to it.

I don't understand the meaning of 'and that is all there is to it'. Besides, I cannot understand the structure either. 'Is', the verb appears twice in this sentence. Would you kind enough to explain it to me?

Thanks,
sweetpumpkin

[Kitosdad]

That the Darrydimples are just down to earth folk in spite of their apparent wealth.

They are just like you and I with no false mannerisms.
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If you need me, I'm here.

[Sweetpumpkin]

Thank you for your attention, Kitosdad. The phrase "And that is all there is to it." means probably "that's all." here. Anne thinks the Dalrymples have nothing special except for their wealth. What I want to know more is the structure of it- isn't it odd that the phrase has two 'be's?

That is all there is to it.

In the context, "that" means what Anne has said, then what refers to 'it' here? Is "there" an adverb or a noun? I really want to know the structure of it.