Question

Thankfully, we had already done our
homework (Identify the sentence)​

Answer 1

Answer:

I have already done it is correct.

I have done it already is not incorrect, but it is unnatural here. When we end a sentence with already, it usually expresses some sort of ahead-of-schedule surprise. But here, you don't seem surprised that you have it done by now. Compare: I can't believe I finished my homework already. Now you are surprised that you have finished sooner than you imagined.

Note also that—informally (and somewhat rudely)—we use already at the end of an imperative sentence to express "hurry up." Like this: Get out of my way already. Do your homework already. Shut up already.