One thing you can do, if you just need an extra creature [perhaps your opponent has used a Barter in Blood and you don’t want to lose both of the good creatures you have, or maybe you’re playing kitchen-table Magic and your opponent intends to use Biorhythm to kill you since you have no creatures] is tap the Keyrune for mana, and use that mana as part of the cost to activate it. It won’t be able to attack or block since it’s tapped when you animate it, but it does count as a body.
Last bit suggested by the submission: Unless you have outside help like March of the Machines, your Keyrunes will never trigger “Whenever a creature enters the battlefield” triggers. They always come down as a non-creature Artifact without help, and turning them into a creature does not count as a creature entering the battlefield [because the Keyrune isn’t entering the battlefield, you’re just changing what it looks like].
Today’s rules tip written by Trevor Nunez, and today’s rules tip suggested by Jason Lems!