In a way, The Revenant has two endings, each of them centering on an important decision.
The first sees Glass deciding whether he will continue pursuing Fitzgerald or give up on his revenge quest. Glass has already shot Fitzgerald once, and he knows that doing it a second time would inevitably lead to his arrest and maybe even execution. That's bad. Thankfully, he's convinced to stand down by Kiowa Brazeau, who appeals to Glass's love of exploration as a reason to hang on to life. Check it out:
"Why did you come to the frontier? [...] To track down a common thief? To revel in a moment's revenge? I thought there was more to you than that."
Still Glass said nothing. Finally Kiowa said, "If you want to die in the guardhouse, that's for you to decide." (2.27.33-34)
The second ending involves young Jim Bridger. Bridger has gained a lot of confidence since the beginning of the novel, and he finally has the courage to ask Captain Henry to be sent on an expedition deep into the frontier. After some consideration, Captain Henry gives him the okay, and Bridger's dream of becoming an adventurer finally comes true.
As you can see, Jim Bridger and Hugh Glass are bonded by a mutual love of exploration. What's more, the decision to close the novel with Jim Bridger staking off into the wild unknown—something Glass has done many times before—shows how important Bridger's character arc is to The Revenant as a whole.