Ty realized something- he had power over everything in the world now. It would be his plaything. He could make any wish he desired and it would reshape according to his will.
And as you might expect of a teenage boy, he had some fun fantasies about how to change it. But he wasn't sure exactly which to go with. Maybe it'd be fun to make it an anthro world? Or to reduce human intelligence to that of animals? On the flipside, maybe he could increase animal intelligence until they could equally coexist (and maybe even interbreed?) with humans. Or he could keep the wish to humankind- change it into a different species, switch around the sexes, change how they aged? First contact with aliens might be fun too- maybe they'd invade Earth, or come to peacefully coexist with us?
Possibility after possibility swirled through his head, but he decided to just pick one to start. After all, if he didn't like it he could use his powers to go back and change it, and switch ideas around as much as he pleased. For now, he focused on what he thought was his most strongly-held wish, specifically...