The Catechism in Questions & Answers

132. What is the significance of Jesus’ temptations?

By resisting these temptations, Jesus already revealed Himself as victor over the Devil before even beginning His public activity.
The first man, Adam, had not resisted temptation. Adam became a sinner, and with him all human beings. In contrast to this, Jesus remained without sin. Thereby He created the conditions required for all sinners to find their way back to God.

Original sin: see Question 482.