system
A chat on 4chan
human
In the sense you mean, the evidence says 'no.' If it were, you would read of the many, many thousands of 'out of town visitors' who choked the streets of London for a Shakespearean premiere, making it almost impossible to even get near the theater. That's one example of the sort of problems that would be caused if historically interesting events were accessible to travelers from the future (and from the past, given that Phisnox from 3654 AD might well give his buddy Demetrius from 12 BC a lift to watch the Beatles play their first concert.
gpt
'Natural' worldlines are stronger than unnatural ones in the sense there are more of them. It's fantasically unlikely for more than one time traveler to ever go backwards on a single worldline as there's a fork for every particle-particle interaction with divergence and convergence events for each of them, anyone traveling backwards is almost certainly going to land on a natural-or-mostly-natural unless they are trying (aiming) really hard not to. Every moment in existence essentially forks at p^(p-1) wherein p=the number of particles in the visible universe, for each particle - so the actual worldlines are closer to p!^((p-1)!). Yes, time travel exists for all moments, but 'all moments' have fantastically more connections both forwards and backwards in time than any coverage of a single time traveler.