The three bears
As mentioned in the fairy tale, the three bears were good and meant no harm. This is why they thrusted everyone and left the door unlocked as well as the window open when they were not home. As protagonists of this fairy tale they are primarily characterized by their appearance (so-called: outer characterization), so we have the big bear, the middle-sized bear, and a little bear. All three bears are male bears and each has its own pot, chair, and bed. We also find out about their character from describing their voices:
The Great Bear has a rough, gruff voice, the Middle-sized bear has a middle voice and the Little Wee Bear has a little voice.
"…said the Great, Big Bear, with his gruff, rough, great voice"
"said the Middle-sized Bear, with his middle voice."
"said the Little, Small, Wee Bear, with his little voice."
Opposite to the bears, Goldilocks as the antagonist of the story is described by her acts. She enters their house uninvited, peeks through the window, peeps through the keyhole, eats food without asking, comfortably sleeps in somebody else's bed. She has certain desires, so she tests everything (from porridge to beds) before fulfilling her wishes. Also, the writer made a comment that Goldilocks could be a thief as if the spoons weren't wooden but silver, she surely would've put them in her pocket.
At best, Goldilocks illustrates the moral of the story: don't break into someone's home, steal someone's food or use their things, because you will be captured and punished. In this version of the fairy tale, Goldilocks was scared, and since the bears didn't harm her, she still decided to jump through the window by herself thus punishing herself, although her faith stays unknown and we don't know if she learned her lesson.