Humanity is being stalked
The introduction to the Galactic Community was... rather awkward. It turns out, humanity had been observed throughout its entire history. With great passion. Far too much passion, in fact.
A member of a very ancient and powerful civilization had been assigned to oversee humanity's introduction and guidance. Instead, she ended up utterly obsessed with humans — every last aspect of them. To a genuinely unhealthy degree.
War and politics? Her battle-hungry soul devoured it all like a TV series, spending evenings with snacks and drinks. Friendship and intimacy? She would regularly select a family to observe, and found herself in tears every time someone had a touching reunion — or a breakup. Eccentricity and perversion? Well, her species is fully hermaphroditic, and she is very curious and very imaginative — she was into everything. It was also her idea to insert tracking devices into human anal cavities.
It is something of a wonder that she maintained her professionalism and was never fully exposed — keeping the fact of her presence firmly in the realm of speculation. (Though the Community has its suspicions about those human legends of dragons demanding virgins as tribute. They simply couldn't prove anything.)
So when humanity demonstrated its capability for FTL travel, the Community was notified immediately — and welcomed humanity into the fold. By law, humanity received a complete copy of their own history, meticulously documented by their ancient, near-immortal observer. Secrets of their origins, reaching back to long before the first civilizations rose on Earth... delivered in the form of a very long, very detailed, and surprisingly well-written romance novel.
Humanity is still trying to get in contact with their eternal stalker. She's simply too good at hiding. The Community apologizes for her, noting that she grew far too reclusive over the course of her extraordinarily long assignment. Though in certain closed networks, human history continues to be documented... in all its vivid detail.