As i understand from the Bible, all human beings came from Adam and Eve. Since Adam and Eve sinned , sin came into the world. Since penalty of sin is death, in Adam we all died. When man was destroyed in the flood, with the exception of Noah and his family, we can claim to have came from Noah, but not even his righteousness was able to save us from death. Man in unsaved stage is called flesh.
But God loves his creation so much that He provided a way of salvation through Jesus Christ and His Spirit to work in us.
God announced the coming of the Messiah (the Savior) through the animal sacrifice even at the time of Abel Adam's second son, and through Abraham, through the law by means of Moses, and through the prophets through the Israelites.
How Jesus Christ is to be our Savior has to be explained in and by. all Christian churches. But before man could receive Jesus Christ as his Lord and Savior, the Holy Spirit has to work in man. One way of explaining this is why Jesus Christ is called the Lamb of God who takes away the sin of the world.
I wish i could talk to you in person about these but you may ask your priest, pastor or your spiritual mentor. If you have none of those, then pray to God that He send someone to help you.