Uploading questions

A vector asset is an asset that describes it's content as a collection of curves that are rendered on the fly on your (pixel) display. Pixel assets like JPEG and PNG files are represented as an array of pixels. Both can represent illustrations, vector assets can never be photos, however.  The advantage of vector assets is that you can size them as needed with no quality loss. 

https://en.wikipedia.org/wiki/Vector_graphics

As soon as your assets are JPEG or PNG files, they are not vector files. That's why you can't upload them as vector. A computer can see the difference, based on the file type, so that is easy. 

Adobe stock allows vector assets as Adobe Illustrator files (unfortuneatly often abreviated as AI), EPS files or SVG files. You can google those formats, if you want more information about that.

Of course. Anything AI that could not be taken with an actual camera (even photo realistic images that would be difficult or impossible to take with a camera, such as composites), would be considered illustrations.

Vectors are created in Adobe Illustrator, frequently abbreviated as AI. Prompting an Artificial Intelligence image generator, such as Midjourney, to create an AI vector doesn't make it a true vector, and labeling it as such when you upload it to Adobe Stock is misleading to Buyers.

So the image that I attached IS an illustration right?

To the best of my knowledge, the Bitcoin image is free and is protected by the Creative Commons license, meaning it can be used for personal and commercial purposes.

No, images created by Midjourney are not AI. Adobe's Illustration app can provide AI vectors.