Jesus' first words to the paralytic weren't about his legs, but about his sins. Why start there?
In Jesus' time, there was a common belief that suffering was a direct result of sin. While Jesus sometimes affirmed a connection between sin and suffering (John 5:14), he also challenged the idea that all suffering was immediate punishment for personal sin (Luke 13:5; John 9:3).
Here, Jesus addresses the deeper spiritual ailment first. He recognizes that the man's paralysis might be linked to sin, but more importantly, he offers forgiveness, which is the ultimate healing. Physical healing is a powerful sign, but spiritual healing—the forgiveness of sins—is the core of Jesus' mission.