There are two conflicting ideals about the salvation of the Israelites. The first is that some Israelites (a remnant) will be saved based on their belief in Christ and their ability to follow Gods Laws. The other is that All Israel will be saved no matter what regardless of their sin:
“and in this way all Israel will be saved. As it is written: “The deliverer will come from Zion; he will turn godlessness away from Jacob.” Romans 11:26
The scripture says that "The Deliver" (Christ) would turn godlessness (sin) away from Israel. Not that they would turn away from it themselves, but that he would turn them away from their sin. In the book of Ezekiel God seems to prophesy a very similar message that he would turn Israel away from the sin that they/we are currently in
"Then you, my people, will know that I am the Lord, when I open your graves and bring you up from them. I will put my Spirit in you and you will live, and I will settle you in your own land. Then you will know that I the Lord have spoken, and I have done it, declares the Lord.’ ”” Ezekiel 37:11-14
I will put my spirit in the dead Israelites and make them live. While we are yet still in sin, he died for us. This is truly a faith that surpasses all UNDERSTANDING. It is a faith that is essentially saying, that God is going to save the Israelites, ALL ISRAEL, no matter what sin we commit right now, regardless of our situation, we will be saved. Damn, that's a radical faith. Look at this scripture:
“For this is the covenant that I will make with the house of Israel After those days, saith the Lord; I will put my laws into their mind, And write them in their hearts: And I will be to them a God, And they shall be to me a people: And they shall not teach every man his neighbour, And every man his brother, saying, Know the Lord: For all shall know me, From the least to the greatest. For I will be merciful to their unrighteousness,” (Hebrews 8:10-13 KJV , Jeremiah 31:31).
God says that he will be merciful to the unrighteousness of the Israelites, that he is going to supernaturally pour out his spirit and place his laws in their hearts and minds. The scripture continues:
"And their sins and their iniquities will I remember no more. In that he saith, A new covenant, he hath made the first old.” (Hebrews 8:10-13 KJV , Jeremiah 31:31)
So they are in sin, because God says that their "Sin" he will remember no more. How can he do this and be a righteous God? For the wages of sin is death:
“In fact, the law requires that nearly everything be cleansed with blood, and without the shedding of blood there is no forgiveness.” Hebrews 9:22
And Christ said out of his own mouth that he was sent "Only to the Lost Sheep of the House of Israel." Making him Israels sacrifice for their sin. This is deep and not all will be able to receive this.
“and it doth not yet appear what we shall be: but we know that, when he shall appear, we shall be like him;“ 1 John 3:2
You are not what you are going to be, You are going to be changed supernaturally, having Gods Laws, Gods Wisdom, his spirit:
“in a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed.” 1 Corinthians 15:52
Juneteenth now established as a federal holiday is the Commemoration of the ending of Chattel Slavery in the United States and given all that our ancestors endured I don't see an issue at all with honoring the sacrifices and hardships that they endured for us to be here today.