...not many apparently.
Explanation:
The 4th dimension is time right?
A dimension is basically something that allows two objects to have some of the same coordinates but not "fall on top of each other".
In X space, object in coordinates 5 and object in coordinates 5 fall on top of each other.
In X,Y space object in coordinates 5,3 and object in coordinates 5,7 despite having the same X, yet somehow are not in the same place.
In X,Y,Z space, object in coordinates 5,4,6 and object in coordinates 5,4,8 despite having the same X,Y, yet somehow are not in the same place.
And so, in X,Y,Z,T space, object in coordinates 5,7,2,4(sec) and object in coordinates 5,7,2,8(sec) might have the same X,Y,Z yet somehow are not in the same place. (very useful when you cross a road)
Now, usually when you try to show a higher dimension in a lower one you usually have a "projection".
The 2d projection of a sphere for example is a circle. And of a wire cube is a shape like this:

Wouldn't a 4d projection in 3d then be basically something like a time exposed photograph then? Only in 3D, so it's more like a sculpture. Which in turn if you projected on 2d, would look like a time exposed / long exposure photograph.
A 4d human in other words, would be a still long, convulted snake thing, with twists and turns according to the 3d places it has/will visited/visit, a
section of which would look, well, like a human.
At one end said snake would start the size of a cell, grow "thicker" and finally break up into little threads when it dies and decomposes.
(for the record, before it started the size of a cell, the two sex cells were two different threads of their own. As are all other components, proteins atoms etc. So in a way a lot of threads come together to a big snake knot kind of thing and then break again)