If you put Bound in Silence onto the battlefield without casting it, perhaps using the “recruiting” ability of a card like Amrou Scout, it will enter attached to a creature. You choose that creature as you’re putting it onto the battlefield. If there’s no creature on the battlefield it can be attached to, it stays in whatever zone it was in.

Bound in Silence isn’t a creature and isn’t affected by any effect that affects creatures or Rebel creatures.