Until the mid 1900's, my life was completely different than the man Christ has created out of the mess He had to work with. Many people that are still alive today who knew me yrs past, they are taken aback by the transformation.
You are correct that some parts of the OT are concurrent, but Christ changed everything. He is the price paid in full for my sins, your sins, and the sins of the world for all times, therefore, when Christ declared that it was finished, He meant that payment had been made in full; hence, there is NO MORE NEED for sacrifice.
'And making a gathering, he sent twelve thousand drachms of silver to Jerusalem for sacrifice to be offered for the sins of the dead-.'
I pray that this clarifies my point further.