Well, if we are anything, it is a verb rather than a noun. To be a person is a living process, not a fixed, unchanging thing that has always existed.

You correct, I am not the same as I was when I was a child. But then a flower is not the same as it was when it was a seed. But to say that the flower existed before the seed is incorrect.

If consciousness existed before my body existed, that means it had none of my memories or personality, and therefore was not me in any meaningful sense. This is why Alzheimer's is so utterly devastating. As their brain cells die, the person slowly crumbles away.