If Jesus has never sinned and has never done any wrong, why did he tell the The Rich Young Ruler that He is not Good and that God alone is good?

And a ruler asked him, “Good Teacher, what must I do to inherit eternal life?” 19 And Jesus said to him, “Why do you call me good? No one is good except God alone (Luke 18:18–19) Why did Christ make this distinction between Himself and God…