[avz]

Single planetary system isn't much more of a protection than a single planet against some of the possible extinction events, e.g. ones associated with the activity of the Sun or intelligent aliens.

> Humanity has survived for 100s of millions of years without as asteroid annihilating us, and I don't see it changing now).

Homo sapiens is thought to have existed for mere 300,000 years. Our last common ancestor with the chimpanzee [1] existed no more than 13 million years ago. K-T extinction event [2] that wiped out dinosaurs happened 66 million years ago. There have been numerous extinction events before and after that [3].

On the timescales of species this planet isn't safe. At these timescales rare events become regular occurrences.

[1]: https://en.wikipedia.org/wiki/Chimpanzee%E2%80%93human_last_...

[2]: https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_e...

[3]: https://en.wikipedia.org/wiki/List_of_extinction_events