Yeah? But that wasn't the end of the movie? Those are the challenges in his way before the end of the movie. Where the moral comes in?

He kills a leopard, proving to the gorillas that he is strong enough to go with them. Their issue (and primarily the leader of the pack's issue) is that he isn't as adept at survival because of his human body. Tarzan was failing their expectation of "survival of the fittest" that they have because they are gorillas. But now they aren't openly ostracising him, even if the leader is still prejudiced against him.

Then the humans come, who look like him. He doesn't have to struggle so hard to fit in, like he did with gorillas. He even fell in love. But then he found out that just because these humans looked more similar to him, that didn't mean they cared about the same things he did. In killing Clayton in defense of his biggest gorilla detractor (and consequently his gorilla family), he's rejecting the apparent human connection and Kerchak, the gorilla leader, finally accepts the sincerity of Tarzan's devotion to community despite assuming Tarzan would side with them.

Everyone learns lessons.

Did y'all just turn off the movie when Tarzan starts walking on two feet?