So I have always been a little confused on the lore of the humans except for the Redguards which to me are pretty easy to understand. Otherwise I was having a little trouble figuring out the origin of Imperials. From my understanding they are people whose blood is mixed with the Cyrodiilic aboriginals and the Nords of Skyrim but I am not even sure how the Nibenese tribesmen came about because I thought it was only the Nords from Atmora and the Raga of Yokuda coming back to Tamriel, but how did the tribesmen come about? Lol please excuse my ignorance in this section of the Lore, but that is why I am posting. Thank you for all of your helpful posts.

You got it about right.

The Nedic peoples (Cyrodiilic aboriginals) were the men who didn't wander off of Tamriel as Elhnofey.

And down the line, two people of Cyrodiil came to be, the slippery, smooth talking, very out going, and magically inclined Nibenese, and the more nordic, down to earth, militaristic Colovians.

And they all lived happily ever after.
The end.

But I thought the Nedic people were the early Nords from Atmora and then started to be called Nords later on.

And wouldnt the Cyrodiilic aboriginals remained as Elves if they did not wander off of Tamriel?

No, the nedics were the native humans of Tamriel. And not necessarily for your wander off comment.

Nope. That's bad Anthropology encouraged by Tiber.