It would be possible to write a macro to insert (in alpha order) and give each an animation of maybe flash once. It's not possible (well not simple) to make the series of animation continue looping it would stop after one revolution. The only simple way is to make the whole slide loop.
How much vba experience do you have. Do you need hints or someone to write the program?
Here is the basic code
Sub do_this()
Dim sFolder As String
Dim sFileSpec As String
Dim sFileName As String
Dim osld As Slide
Dim opic As Shape
Dim oeff As Effect
Set osld = ActivePresentation.Slides(1)
' Edit this to suit don't miss out the last \:
sFolder = "C:\Users\John\Desktop\Pics\"
sFileSpec = "*.JPG"
sFileName = Dir$(sFolder & sFileSpec)
While sFileName <> ""
'numbers are left,top,width and height edit as needed
Set opic = osld.Shapes.AddPicture(sFolder & sFileName, False, True, 10, 10, 120, 100)
sFileName = Dir()
Wend
End Sub
You will have to do more work to make the movement controllable. Probably by moving the correct image to the front based on the value in a spin button.