Core temperature might vary between people by only a few degrees, but surface temperature varies much more widely.
That's an interesting point. Would you agree that if a person has a higher metabolism, one would expect that under your theory, their skin temperature would be expected to be higher?
That, and/or increased sweating, and/or larger temperature gain between inspired and expired air, or wearing fewer/thinner clothes. There's lots of ways to dump heat.
I would definitely expect someone with a faster metabolism to put out more total net heat, which is measurable with difficulty, and also consume oxygen faster (and produce carbon dioxide faster) which is measurable with some difficulty, but a lot less.
What is something you used to believe, preferably something concrete with direct or implied predictions, that you now know was dead wrong. Was your belief rational given what you knew and could know back then, or was it irrational, and why?
Edit: I feel like some of these are getting a bit glib and political. Please try to explain what false assumptions or biases were underlying your beliefs - be introspective - this is LW after all.