Demons, in this short poem, aren't the creatures we meet in nightmares. They are people. The speaker looks back at the frightening figures we imagined as children, or in our sleep, and realizes that the real danger was never supernatural. It was hiding in ordinary human form.
The speaker sounds quietly disillusioned. The word "nobody" points to a gap in how we're raised: adults warn us about monsters under the bed, but no one prepares us for the people who can hurt us. There's no shouting here, just a flat, almost tired tone, as if this is a lesson learned the hard way. The line "masked as humans" is the sharpest image, suggesting that cruelty can look friendly or normal and that we may not see it until too late.
The mood is unsettling and bleak, but also calm. The short, broken lines leave pauses that make the final idea land with weight.