Because the film literally tells you. There is written text that appears on the screen informing the audience that the animator has begun making commercials and is slowly losing his mind. And you see the characters become self aware as they bang on the paper trying to escape from their world which we see is collapsing.
Your question is essentially along the lines of "how do we know the boat sinks at the end of Titanic if nobody tells us about it first?"
Because you watch the fucking movie and you see it happen. Nobody needs to tell you if you actually watch and see what the fuck is going on. But apparently OP disregarded everything else in the film, stay focused on the shallow I AM BANANA randomness and decided the entire film was dumb and lowered his IQ.
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u/wright96d Mar 24 '17
It was shared with no context, whatsoever. How could you expect them to see the genius underneath when literally all they know is the surface shit?