We need Jesus because we have sinned against God. We rejected our Creator and have denied Him His rightful place in our lives. Instead we have turned in our hearts from Him to be our own gods, to seek our own significance, purpose and happiness apart from Him. Because God is holy and just, sin cannot be in His presence. So we are separated from Him and have only judgment, hell and His wrath for our sin waiting for us after we die.
But because of His great love and desire for relationship with us, God sent His Son Jesus in order to provide a way for us to be restored to Himself and become His children, now and forever, in His eternal kingdom. Jesus lived a sinless life then went to the cross where the Father placed all of our sin upon Him. Because of our sin Jesus was separated from the Father for the first time in all of eternity and then He experienced the wrath of God for every sin then He died. Since Jesus had no sin of His own, after He had paid the penalty for every sin, He rose from the dead proving He was the Son of God and that He had overcome sin making salvation possible for us.
In order for us to receive salvation we need to recognize that we have sinned against God. That we have rejected and rebelled against our Creator to be our own gods. We need to confess it to ourselves and to God and then we need to turn in our hearts from sin back to God. Then we need to put our faith in Jesus and all that He did for us and embrace Him as our savior and king and live life accordingly.