Juneteenth is interesting for many reasons. One of those reasons is in the way it differs from a celebration of emancipation.
It is not a celebration of emancipation, or in fact a celebration of any act by an oppressor culture. Instead, it commemorates the fact that if you are an oppressed group, you cannot rely on your oppressor to give you a square deal.
In that sense, it is very particularly a celebration of, for and by this particular historically oppressed group. The attempts by everybody else to join in, however well meaning, maybe misguided.
If you are not part of an historically oppressed group, this distinction might not make sense to you. But if you are, it will seem obvious.