Ok looks like they're the centrifugal pins from the starter clutch. Since they're not chewed up it's doubtful they're the reason the engine seized. So my guess is they just fell out sometime and they resorted to kickstarting the bike.
Parts 12,13
Edit:
Not really sure how these could have fallen out during normal use. Perhaps someone changed the starter motor at some point? I can imagine that they fell out when I was taking the motor apart but I took the oil pan off before I removed the starter.
Anyhow! This is all a sort of filler because the main attraction here is the Ninja! Patiently awaiting the new parts to arrive.