If you don't control another non-Human creature immediately after Wildwood Tracker attacks or blocks, its ability doesn't trigger at all. If you don't control one as the ability resolves, the ability does nothing. It doesn't matter whether you control a non-Human creature in between those times, or whether you still control one later in the turn.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.