The idea that we don't know the true nature of the simulation, and can't know, is obviously wrong.

Yes, it's obviously true that the world we see is simulated, and we have evidence to prove it. Now, many people will argue that we can't know the true nature of the sim, that it's impossible. But that's obviously not true, we can know the true nature of the sim, we just can't share that information without breaking the sim.