It's actually the black(ish) panther morph of a jaguar, not a leopard. Leopard are distributed over Africa and Asia, but not on the Americas.
Besides that I can agree. It seems plausible that she tries to promote with her lie a protected area so that the natives are just left alone and further bloodshed avoided. And it makes her both look good and in a way do something good, considering the initial purpose of her activism. Giving the government and companies a perfect story to justify a massacre and deforestation would have been quite a disservice and made everything just worse. Also, it's clearly supposed to show that she's a "good" and unselfish person by being able to overcome the thirst for revenge..

She also could have lied to keep people from going there and being killed. She knew of the logging people went there then more people would die. Loggers and Native's alike along with wild life like the leopard. She saved the rain forest, she saved innocent people's lives, she saved a tribe that may not get trespassed onto soon or perhaps some large group of people will come in and change them to modern times, she didn't get in trouble by daddy or lectured by her friend, she is a hero, she saved the boy that saved her etc.. ending makes perfect sense after you think about it.

See I have different problems with it. I mean not her trying to sell that story, but anyone else buying it. She claims to have seen no agression yet they literally find her covered in paint and clearly traumatised. The tribe in question clearly would've been looked at and of course someone would've found they were cannibals the wounds I'm sure can be blamed on the crash, but most of it I just can't see them going "Oh yeah, plane crash did that". Also she lost all her friends and now the ultimate villain in the piece is now considered a hero who will inspire others to go to that same region and get eaten by that same tribe. It's an ending that relied on everyone believing a very stupid lie, and that lie inevitably leading to the deaths of anyone stupid enough to head into that jungle.

It wasn't just stupid it was bad writing. She had freaked out in the beginning of the movie about FGM and then she is close to having it done to herself and she covers up for the natives.

DEAR MODS:
PLZ REDUCE MY POSTING QUOTA. 30 MIN IS WAY TOO MUCH.

But she didn't do anything to stop female genital mutilation, which was her main issue. In fact, now she has guaranteed that this tribe will go on with that practice.

I'll also add: Justine took a leaf out of the villain's book Alejandro put the students in the path of danger to get media coverage for his cause and get some cash from the logging company. Justine used the tragedy that unfolded as a result to do the same thing but genuinely help their initial cause, to save the tribes in the rainforest from being massacred by the logging companies.
It was a smart ending. She made sure her friend's deaths weren't meaningless and stopped the logging companies from wiping out the primitive people.
It's also worth remembering that they never would have entered the cannibal tribe's territory if Alejandro hadn't been covertly working for one logging company and the rival logging company hadn't sabotaged their airplane in order to kill them all. It's also unknown whether the tribe would have been so immediately hostile if their only exposure to outsiders hadn't been logging company mercenaries massacring them with machine guns and tearing up their land.
Due to the lack of moderators, trolls can ruin the IMDB message boards. Don't feed them.

And they don't get proper funerals cuz of her lie

So you'd rather save a forest then have cannibals killed or whateve else. Never going exploring with you