Change can be instantaneous. Change can take centuries. Sometimes a change appears instantaneous when the truth is one or more people have been working on the change for a very long time. The longer something has been stable, the more difficult it is to change and the longer it may take to change.
We sometimes try to change something and discover it remains the same. We will have found on our life journey it is best to learn from this and to never assume it will remain the same forever. Without additional action, we may find the change long, long afterward.
We may not become aware of a change. That does not mean we made no impact. It may simply mean we do not know about it. A perspective on what we do not know is much more important than what we do know.
The impact each individual has on others, both present and far into the future, is much greater than is known. We shall rejoice as often as we can in the positive impact we will have had on others, some of which we will know nothing about (while on this earth).