Not a problem, for it’s too hard to answer and it’s perhaps too vague, but a question:
The concept of a knot arises in 3D. There is nothing like a 2D knot, it is meaningful only in 3D and beyond. You can knot “2D 4D flat” objects in 4D, just as you can knot “1D 3D thin” objects, also known as ropes, inside the 3D world. You need 2 codimensions to do that.
Now, what’s essentially new in 4D space, which is unimaginable in 3D world. What arises there?
Answers like “two chained rings can be unlocked” don’t count. Because we already have interlockings in 2D which are easily unlockable in 3D.
What is essentially new and fresh inside the 4D world, we can’t imagine here? Or we can’t imagine, but have some clues about that?
Should be at least something. What could that phenomena be?