What you are trying to say is not clear at all, so it feels like an idea popped into your head and didn't get vetted before it got written.

"The rest is the historian format (gives specific dates, gives specific names and the name of the era)"
This fails at legend as hard as you can fail at legend.  If you have specific dates you have a history lesson or news report.
Legends happen at a time when a story could not be recorded  and thus got passed on as a story by word of mouth. This is how you get "long long ago" and "Long before our father's fathers did X.." story teller after story teller takes the story and embellishes it as they pass it on.

" There are three possible ways a legend (for a first chapter) can be told. The first is the perspective of one of the main character or supporting character"
Absolutely not. That is a story not a legend.
A legend is told as a past event whose details have been inflated by getting passed from story teller to story teller. A direct account is just a story even if that is how some legends start. Think of Jack the Giant Killer in this regard, this covers how a story becomes legend.
The difference between legends and fairy tales is that legends are claimed to be true. A good legend is a fairy tale.