Here Jesus being man e.g flesh, and according to some died to fulfill the law, doing a work of the law. If the case is that in order for mankind to be saved through Jesus Christ he had to finish the works of the Law, fulfilling the law, how is it anyone is justified since no flesh will be justified by works of the law?
"because by the works of the Law none of all flesh will be justified in His sight; for through the Law is the knowledge of sin. But now a righteousness of God has been revealed apart from Law, being witnessed by the Law and the Prophets" Rom. 3:20-21
Flesh could not do God's law so God's law did the flesh (i.e. the Word was made flesh)
"For what the law could not do, in that it was weak through the flesh, God sending his own Son in the likeness of sinful flesh, and for sin, condemned sin in the flesh Rom." 8:3
So that whosoever will receive Him receives the cancellation of debt for being transgressors of God's law:
"When you were dead in your transgressions and the uncircumcision of your flesh, He made you alive together with Him, having forgiven us all our transgressions having canceled out the certificate of debt consisting of decrees against us, which was hostile to us; and He has taken it out of the way, having nailed it to the cross." Col. 2:13-14
And power to engage God's word (aka righteousness) with an increasing measure of freedom from the desires of the flesh---it now being circumcised.
"That the righteousness of the law might be fulfilled in us, who walk not after the flesh, but after the Spirit." Rom 8:4