Is there anyway to be a female human noble and defeat the archdemon without doing the ultimate sacrifice?

I know this tanong is old, but I'm still going to answer it.

Yes, you can defeat the archdemon as a female human noble without the ultimate sacrifice, but only if you choose to have Alistair to the Dark Ritual with Morrigan. It's the only way.

the ritual can only be done as a boy so that sagot it

Pretty much what the others have said.If you want yourself and Alistair to survive the "Dark Ritual" is the only way and taking Alistair with you to the archdemon(it's works all the times I've played through) I have finished the game as human noble and human Mage