Juneteenth was not a part of my education growing up.
My understanding is that on June 19th, 1865, the news of the 1863 Emancipation Proclamation
finally arrived at Galveston, Texas: although they had been free persons for more than two years, the reality that all people are created equal had not been effectively communicated to the enslaved and the slavers.
It seems to me that this concept of a delay in understanding is somewhat apropos of our current American reality: even today, not everyone has received and accepted the message that we are all, equally, in God's image and should behave towards each other appropriately.
As Jews, the best guidance for what we should do comes from a Lutheran Pastor, Martin Niemöller. These are his words, as quoted by the United States Holocaust Museum:
First they came for the socialists, and I did not speak out-because I was not a socialist.
Then they came for the trade unionists, and I did not speak out- because I was not a trade unionist.
Then they came for the Jews, and I did not speak out-because I was not a Jew.
Then they came for me-and there was no one left to speak for me.
Now they have come for the Blacks, and it is our duty as Jews - and as people made in God's image - to speak out: Black Lives Matter.