"The payoff of sin is death .. " (Romans 6:23a).
It is sin that causes death (Romans 6:23; 1 Corinthians 15:56; James 1:15):
-- "Just as sin entered the world through one man - and death through sin - death spread to all people, because all sinned." (Romans 5:12) --
Not only did all the offspring (all descendants) of the first humans sin IN Adam, but "all have sinned, and fall short of the glory of God" (Romans 3:23).
(Anyone who has ever had sinful thoughts and desires, told lies, or broken one of the other ten commandments, or committed any other sin, is a sinner: Jesus said, "For out of the heart come evil ideas, murder, adultery, sexual immorality, theft, false testimony, slander." -- Matthew 15:19).
In other words, if we ever have things going on in our hearts and minds that are sin in God's sight, then even before we commit sin and become sinners,, we have been sinful, inwardly (James 1:15);
and "the payoff of sin is death .. but the gift of God is eternal life IN Christ Jesus our Lord." (Romans 6:23).
--- ---