Well, for large creatures they used crossbows which would be ideal for the modern man as they require no training and easily have the firepower to punch deep into a bear.
A medieval crossbow power depends on its draw weight, which depends on the method of drawing the bow and so will determine its speed.
A stirrup takes the longest to draw as it is drawn with your foot holding it down while you draw the bow towards you with two hands. It has the power to punch through even the thickest of plate armours if the blow was direct enough. Probably 5/6 seconds to draw but you can be sure that if you hit the bear in the chest its probably going to kill it... but unless your lucky not before it kills you.
Cranequin is the next one up with a hand crank to draw it. Easier to draw but probably takes just as long and has less power, though enough to punch through plate armour too.
Push/Pull lever ones are probably ideal for most of these situations as they have the stopping power but are far quicker to load. It might not go all the way through a bear skull but you can probably load it a few times quicker than the above.
For the wolves i would have to think a spear. They use to use spears to hunt as it kept animals at a distance and it takes next to no training to train someone at using a spear.
If you think using a shield will help you, then your doing it wrong

. Shields were always used against other people not animals, they shouldn't get that close to you and if they did, then you have a cumbersome thing preventing you from using two hands for wielding a weapon quicker or just moving out the way with ease. The reason why small/medium swords are not useful is that a sword requires training and hitting a moving target with enough momentum, at the right angle to sever bone is difficult. Gorillas and bears are thick and chances are you will end up going in range only to a deliver non fatal blows against a big wall of flesh, muscle and bone, only to receive a vicious counter.
Edit:
Crossbow draw-weight from the medieval period is up to 740lb
https://www.google.co.uk/search?q=m...me&ie=UTF-8#q=medieval+crossbow+draw+weight&*
Recomended Draw weight for Grizzley bears and mooses and such is 200lb +
http://www.streetdirectory.com/trav..._weight_do_i_need_for_crossbow_hunting63.html
Plenty to spare, just dont miss as unless you are a big guy, you will struggle to **** a high power crossbow unless you use a crank or a stirrup which are really slow.