This is "what if?" alternate history Tarzan story.
We can basically cut to the second act of the Disney Tarzan movie set up Tarzan is interested in Jane who is part of a research expedition lead by the prolific hunter, Clayton. Clayton's trophy room mimics the Predator's. While Tarzan and Jane are bonding and he is showing her the wonders of the forest, he warns her of the poison frogs, flesh-eating ant mounds, and the nearby active volcano basically establishes all the set pieces used later in the story.
Predator shows up, looking to take down Clayton who we see as a great hunter through Predator's eyes. This in turn endangers Jane which gets Tarzan involved. He tries to defend Clayton with his makeshift spear, but even with both of them fighting, Predator gets his way and Clayton is killed and his spine ripped out.
Realizing he is a skilled fighter to have stayed alive longer than Clayton, predator turns his focus to Tarzan who lets out his famous call, signaling