Start with high-confidence how the human body works books, then narrow by subgenre or adjacent topics.
The Story of the Human Body
Daniel E. Lieberman
Breath
James Nestor
The Body
Bill Bryson
Masters of the Planet
Ian Tattersall, Bob Souer
The Eating Instinct
Virginia Sole-Smith
Why We Sleep
Matthew Walker
Unsavory Truth
Marion Nestle
Introduction to Kinesiology
Duane V. Knudson, Timothy A. Brusseau
Protocols
Andrew D. Huberman Ph.D., Andrew D. Huberman