Comparing this movie with Ex Machina, on the later we have Ava being locked ever since she was created, for no apparent reason other than precaution, and it clearly made her not trust her inventor and look into doing whatever she could and lying as best as she was able to get free.

Here we have Morgan being raised with love and free on the forest. It seems she had done nothing bad until she killed the deer, which made everybody scared and they locked her for safety. When her friend was talking to her explaining she was trying to convince the others to release her, Morgan attacked her for no apparent reason. Throughout the movie, Morgan keeps regretlessly killing ppl who cared for her and did what they could to save her, but they were also scared for knowing she was a weapon and designed to kill.

I wonder if Morgan was doomed to follow her programming and would kill and keep killing even if they had not locked her, and if she was lying while locked, as Eva was, or if it was all a misunderstanding which got very bad. Maybe she killed the deer to end its pain, attacked the girl because she was mad, and then murdered everybody because she considered they were not friends of her because friends wouldn't lock her and because they did wanna kill her. So, a misunderstanding led them into overreacting and their actions destroyed her trust on them. And, if they had reacted better, she'd apologize for a sad behavior and it'd all follow nicely.