New Creation represents all the collective new that was purchased by the resurection of Jesus from the dead - a second creation - it is the ultimate relacement for the orginal creation that was ruined by the disobedience of Adam and Eve in the Garden of Eden.
John 3:16, may have said it best when Jesus said,
"For God so loved the world (cosmos) that He gave His only begotten Son, that whosoever believes on Him should not perish, but have everlasting life."
While the present, old creation will continue to the end, Christians enjoy the life of the new creation in foretaste, awaiting the full manifestation of the new creation at the resuurection in the end, and the passing away of the old creation.
Jesus essentially said that His Father absolutely loved His original creation in its perfect form as given to Adam to rule. But when Adam gave His dominion to Lucifer at the fall, the Father's beautiful creation was poluted with sin and darkness. The Father sent His Son to be the Second Adam of a new creation; becoming the prototype over the new creation (Colossians 1:15; Revelations 1:5.). He would buy back dominion through His death, and redeem everyone who would accept His death on their behalf, inviting them into a new creation that would have its start in this life, and its fulness in the future on a renewed planet earth. Today, the brothers and sisters of Christ live out their newness with an influence onto the old around them in anticipation of tomorrow. If anyone is in Christ, there is "new creation" (2 Corinthians 5:17; Galatians 6:15.)
When a sinner accepts the sacrifice of Christ on their behalf, they are given a new, soft heart. The stony one is replaced. They are also giventhe Holy Spirit as a deposit on the inside, a witness and a guarante, that the New started inside, heavenly redeption, will truly have all its fullness, no matter what they go through in this life. The Apostle Paul wrote to Timothy:
"For I am persuaded that he is able to keep that whcih I have committed to him against that Day."
Christians become representatives in part today of tomorrow's new creation in full. Christians are ambassadors in their churches as they walk in love towards one another. That love today in an imperfect world shining onto this old creation is a picture in part of what it will be like when the old creation has passed away, and the New Creation has come into its fullness, filled with God's love, when God is able to fill everything with His love in practice.