Some Bibles use the word "creation" in 2 Corinthians 5:17 because the persons doing the newer versions did not understand the difference of these two words. You are a creature to begin with. If you didn't already exist, God would've had to create you and then you would've been a creation. But you do already exist and God didn't change you.
I've heard others say this and I have said it myself: "When you are born again, you're a brand new creation." No, you are not a brand new creation, because your body and your soulish realm are exactly the same as they always were ... they have already been created.
The "creature" is one part of the 3-part being, but it's also part of the whole. We are three parts: spirit, soul, and body. But the creature part of us that we're talking about here is our spirit.
It's like God the Father, God the Son, and God the Holy Spirit. They are all One, but They are different parts. God, all three parts, work as One.
Like the United States government: three parts: the Senate, the House of Representatives, and the Judicial, one government. They work as one.
Reverend Robert W. & Mary C. Butler