And so on. The point is that the entire battlefield is intended to be seen and represented from a bird's eye view, which isn't how it is portrayed in fiction.
Here is how a battle between those same characters would actually play out in a movie:
The camera shows enemies 1, 2, and 3 moving towards hero A; hero B moves in and cuts off enemy 3
A fast and furious exchange is shown between hero A and enemies 1-2
The camera switches to show hero B dueling with enemy 3
Change in view, and hero C (not a warrior) is being chased around by enemy 4
Change back to hero B finishing off enemy 3
Back to hero A, who has defeated enemy 1, but is now on the bad side of the fight with enemy 2, when suddenly hero B jumps into the engagement and they team up and take out enemy 2
Switch to hero C who is on the ground up against the wall while enemy 4 is raising his weapon to finish him off...then his gaze goes blank and he slumps over, and you see hero A standing there, having just hit him in the head with the butt of his weapon
What's the main difference here? The difference is that instead of getting a bird's eye view of the battle, you get camera angles (or descriptive paragraphs in a book) switching from different engagements between heroes and opponents. Initiative only matters within an individual engagement.