You need to adjust the keyframes in your ‘main scene’ comp.
In the ‘boy running’ comp, your workarea loops between 05:00 and 05:11.
You need the keyframes in ‘main scene’ to match.
Open ‘main scene’. press U to display keyframe. Move the playhead over the first keyframe and change the time (in the left panel) to 05:00. Move the playhead over the second keyframe and change the time (in the left panel) to 05:11.
Move the keyframes closer together for a faster animation.