It was poor decision making of the staff and the parents of the child who got Harambe killed.

That's pretty metal bro.

The kid split into the good universe, where none of the violence ever happened, played patty-cake with Harambe for a bit. Then went on to live happily in a world with universal rights, a healthy and stable ecology, and only distant memories of war.

Most likely either dead in this universe or just another soulless doppelganger existing only as paradox prevention.

Prison

Considering who he was being raised by, he's probably going to turn out to be a problem that society will be needing to deal with at some point.

They probably have no recollection of that event xd