Put another way, how many truly first-thought-of ideas does the average human think about? For example, as a kid, I thought of a TV-watch, only to find they exist, so I couldn't have been the first to think about it. Whereas, the thought that "I declare 1+1=75738529014" could be assumed original.
The human brain has some unbelievable features, but is there any scientific explanation when two people frequently say the same words at the same time or perform the same action in synchrony without meaning to, as if there was a "link" between the minds?