system
Given the following post, respond as if you're commenting on Reddit:
human
[LOTR Movies] Is the prologue a dramatization, or did Sauron actually try to reach for Isildur instead of just killing him?

If the latter, why? 

My headcanon has been that it is the former, told in the way of an epic myth or legend where details aren't as important as the larger story (Galadriel narrating that way helps too). It would also explain things like how Bilbo finding the ring only looks passably similar to the 'real' version.
gpt
Sauron had just killed his two greatest enemies in Middle-Earth - Elendil lay broken on the ground, and Gil-Galad was literally burned to death from the heat of Sauron's hand.  Gil-Galad's death was mentioned in the books and was planned for the films, but was eventually left out.

Odds are that in his moment of triumph, Sauron was riding a high and wanted to make a show of killing the greatest Man still standing on the battlefield - probably intending to lift Isildur up and burn him to death as well for all to see, demoralizing the Free Peoples and emboldening his army of orcs.  He would have thought him self nearly all-powerful in that moment, which is a great weakness shared by the evil powers in Middle-Earth - one that often leads to their downfall.  His greatest servant, the Witch-King, would later fall victim to that same prideful thinking, believing that he could not be slain.