It's quite complicated. Interesting read:

https://en.wikipedia.org/wiki/Heat

I don't think the radiation heat transfer from microscopic bodies is the same as saying a human body emits infrared light on a macro scale.

It does though, that's how infrared cameras work for one thing.

I think this is mixing up two different things.

People seem to emit infrared light, but that is not the light that people usually see through an infrared camera.

https://www.livescience.com/7799-strange-humans-glow-visible...

This is showing infrared and even visible light radiation from a person's body in extremely small amounts.

An infrared camera just sees infrared light period, the vast majority of which is what is reflecting off of someone from other sources.

Generally speaking, warm/hot objects radiate in the infrared range. In my understanding, all objects radiate something, unless at absolute zero.