Keyframes are reusable — copy them from one layer and paste them onto another without animating from scratch each time.
Steps to copy and paste keyframes
Select the property with the keyframes you want, highlight them in the timeline, and press Ctrl+C (Windows) / Command+C (Mac).

Move the playhead to where you want them, select the same property on another layer, and press Ctrl+V / Command+V.

The animation is now copied over and applied to the new layer.

One more thing
You can even paste Position keyframes onto a Shape Path — After Effects will interpret them as motion paths and apply them correctly.
Related how-tos
How to add keyframes in After Effects
How to stretch keyframes in time in After Effects
How to use the graph editor in After Effects
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