sincere, kind, considerate
惇 centers on a warm, genuine goodness of character: being sincere, kind, and thoughtfully considerate toward others.
惇 combines 忄 (heart/mind) with 享, which likely contributes the sound and carries a sense of receiving or offering, together suggesting a sincere, kind heart.
The heart radical 忄 beside 享 (which can suggest offering or receiving) paints a picture of a heart that gives genuine warmth: sincere, kind, and considerate.
For シュン, imagine a kind person named Shun who always offers sincere help: Shun -> シュン, and his heart 忄 is full of genuine care.