The older kid on the bus who was nice to you when you were small was teaching you how to treat the next one.

Older kids set the terms by example. Being treated decently when you were small and nobody had to bother tells you what normal behaviour looks like, and you carry that version forward without ever deciding to. That is how the culture on a bus, in a team or at a school gets handed down. Every age group is teaching the next one how to treat the one after that.

You are now the older kid for somebody. Be deliberately decent this week to whoever is youngest in your group. Learn their name, make room, and do not join in when they get picked on.