I believe you may be overthinking thOse things which you have written about.

You wrote, "Since He's seated at the right hand of the father, is it safe to say that a man is currently part of the Godhead? What were we meant to be before sin spread its long shadow? And what might we be when that shadow finally lifts? Does this mean humanity was meant to share in divinity?"

The first verses of 1 John answer your first question.

In addition, Son of Man, Son of David, Son of God all refer to Jesus in fulfillment of Scripture. He is the Seed promised to Eve. He is the everlasting king [promised to King David. He is the promised Messiah, the Son of God, birthed by Mary but conceived by the Holy Spirit.

Now, Jesus was never not God.

You are close at the end, because 2 Peter 1;4 reveals the fact that "Through these he has given us his very great and precious promises, so that through them you may participate in the divine nature, having escaped the corruption in the world caused by evil desires."

We are children of God but not Divinity itself, but in our nature: "Dear friends, now we are children of God, and what we will be has not yet been made known. But we know that when Christ appears, we shall be like him, for we shall see him as he is."

Like the angels , we are still created beings, so we will still exist as created beings.

2 Peter 1:4 (NIV) - "Through these he has given us his very great and precious promises, so that through them you may participate in the divine nature, having escaped the corruption in the world caused by evil desires."