The Real Sandwich

Sandwiches have evolved rapidly over the ages, ranging from such classics as a plain ham sandwich on white bread to a highly complicated half-toasted Reuben with thousand island dressing, specifically prepared sauerkraut and corned beef cooked to absolute perfection.
However, what was the very first sandwich?
My illustrious sources indicate that the first successfully created, widely accepted sandwich was thusly;
The Toasted Cheese Sandwich.
Boring, right? However, as I said, we are looking for the FIRST sandwich, not the first "successful" sandwich.
Thus, as I have traveled far and wide to research this, I have come to a stunning conclusion:
there isn't one
lmao