From the Friends of Algonquin page on bears:
Although Black Bears are reasonably common in Algonquin Park with the population thought to be around 2,000 (about one for every three square kilometres) there is no particularly good place for them and you will have to be very lucky to see one.
In most cases, a bear will hear or smell you before you are aware of it. Even if you surprise a bear, it will most often flee the area. Reacting to a fleeing bear... Enjoy the fleeting sight of a wild Black Bear.
As for wolves, they hold "wolf howls" where they try to get a pack to answer, but throughout August and September of this year they were not able to find a pack that would respond. Your chances of seeing a wolf with your eye are therefore very low.
Finally on the matter of snakes, there are no venomous snakes in Algonquin. Any snake you can see there is not dangerous. I've been going to Algonquin for over 30 years and have never seen a snake there. (Nor, for that matter, a bear or a wolf, and I go backcountry.)
For the record, I have seen bears: in a park called Wakami (much more remote than Algonquin) and in my own backyard not ten feet from my deck. "Enjoy the fleeting sight of a wild black bear" is appropriate advice. I have only seen dead wolves, and not in Algonquin, but on Ontario sideroads. I hear coyotes calling almost every night in my rural Ontario property and yet have never seen one (again in over a quarter of a century) and don't feel endangered by them in any way. (They do eat cats though.) I have been lucky enough to meet a moose several times in Quetico, and unlucky enough once on a highway (we managed to stop in time but it was terrifying.)
Enjoy the trails of Algonquin. Do be smart with your food, and then stop worrying about animals.