"And it was on record in America as law that we as black people were not considered fully humans."
This is something that people continue to say that is not really true. The "3/5 Compromise" is where slave holding states were granted the right to count 3/5 of their slave population when apportioning the number of a state's representatives in Congress.
It never mentioned anything about the humanity of Black people/the slaves. It really was about taxes and how much each state would be taxed.
Racist people spread the propaganda that Black people where less than human and cherry-picked wording from the 3/5 Compromise to falsely claim Congress had enacted a "law" proclaiming such.
You are technically correct about the 3/5 compromise, but there are numerous examples in state and federal laws, as well as judicial rulings that certainly communicate that blacks were not viewed as fully human. For example, look at the text of the Dred Scott decision of the Supreme Court:
"a negro of the African race was regarded by them as an article of property, and held, and bought and sold as such, in every one of the thirteen colonies which united in the Declaration of Independence and afterwards formed the Constitution of the United States."
"they [blacks] are not included, and were not intended to be included, under the word "citizens" in the Constitution, and can therefore claim none of the rights and privileges which that instrument provides for and secures to citizens of the United States. On the contrary, they were at that time considered as a subordinate and inferior class of beings who had been subjugated by the dominant race, and, whether emancipated or not, yet remained subject to their authority, and had no rights or privileges but such as those who held the power and the Government might choose to grant them."