Prof David Hawkins has an explanation for this (He's a consciousness researcher).

His theory (I don't remember if there were experiments done to prove it) was that "energy fields" operate through humans (we're conduits for said fields).

These energy fields can be thought of as different radio frequency bands for different levels of consciousness - so at any given point, the consciousness-reveal for any given discovery happens at the energy-field level - so different humans who've "tapped" into the same energy field end up arriving at the same conclusions/discoveries.

I haven't explained this anywhere as well as David Hawkins has