I would have focused almost exclusively on the founding of the Federation - no exploration into the unknown.
I should make it clear up front that I'm heavily borrowing from TheGodBen
's ideas he listed in his review thread some time back and altering them slightly - I have little orginiality, sue me.
First, I would start with Humans as an established player on the interstellar scene, but a very, very minor (almost third rate) power - much like they were at the start of ENT Season Four.
They would be on friendly terms with several neighboring races, mostly Vulcans and Andorians. I would hint at the fact that the Vulcans and Andorians were once bitter enemies, but wouldn't spend that much time developing the antagonism, because by this time they've overcome those past problems. I'd also hint that it was Humans who helped bring an end to hostilities, but again wouldn't focus on it - that's just background.
I'd start the series with an episode very similiar to Babel One
. The NX-01 is escorting high ranking Andorian government ministers to yet another peace conference with Vulcan. The NX-02 is travelling along with them, escorting high ranking Vulcan government ministers to the same conference, which is being held in neutral Tellarite terrority. Humans have never had contact with Tellarites, so this will be their First Contact. The Romulans, anxious to splinter any harmony in the local instellar area, even this little amount, send a small fleet to destroy the the Vulcan and Andorian conference. This results in a very tense engagement above Tellar Prime, as the Romulans thought the Earth ships were simply carrying the ministers, not escorting a mini-fleet of Vulcan and Andorian ships. On one side sits the Romulan fleet and on the other sits a fleet of Vulcan, Andorian and Tellarite vessels, along with Earth's two top ships. As TheGodBen
said.... "It's a hugely tense moment, this could be the outbreak of the Romulan War, all it would take is one captain on either side to have an itchy trigger-finger. In the end the Romulans back down because it's not in their interests to go to" full scale "war" against a coalition like this yet, "but the humiliation they suffered that day strengthens their resolve to break this alliance and take revenge upon Earth" and her newfound allies.
As for the Romulan War itself, I don't know how I'd handle it - other than it would have to be fought through drone-ships and intermediaries fighting for the Romulans. It would end however, in a massive, decisive battle on the outskirts of Earth's solar system about two or three years later. Dozens of drone ships and dozens of intermediary ships (Nausicaans and other mercenaries) head toward Earth in a last ditch attempt to destroy the alliance, which the Romulans believe is being held together by Humans. The Romulan forces are defeated in orbit of Pluto its moon Charon by a combined force of Human, Vulcan, Andorian and Tellarite vessels under the command of Jonathan Archer. I'd also have the NX-03, NX-04, and NX-05 take part in this battle. I'd would retcon this to be the Battle of Cheron, mentioned in TNG: The Defector
, with military and government officials on Romulus mispronouncing the name of the moon over which they were defeated.
I would also expand on Section 31, showing their origin. As TheGodBen
said.... "The colony in the Alpha Centuri system is humanity's largest outside the Sol system with a population of 50 -100m people, and it is also vital to Earth and Starfleet" as well as the war effort against the Romulans "because dilithium has been discovered there, which will be vital for the construction of the warp 7 ships currently on the drawing-board. For some reason the colony wishes to secede from Earth's control, but Earth, and Starfleet in particular, cannot allow this because they need the dilithium which" is found in only miniscule quantities inside "the Sol system. Some Admirals in Starfleet meet in a dark office and hatch some sort of plan to prevent Centauran secession, and they bring it to the" United Earth Prime Minister "in a secret meeting, pointing out that Article 14, Section 31 of the Starfleet charter allows such an action to take place. The" Prime Minister "sanctions the action, which I feel is important because it gives Section 31 a certain legitimacy that they don't have if they're only a group of Starfleet Intelligence operatives gone rogue."
"I'd even go further than all that and make sure that future story arcs" after the war "show that this small but growing group in Starfleet (Reed gets recruited at some point in the show) is instrumental in the formation of the Federation. Without Section 31 there wouldn't even be a Federation" (possibly bringing about regime change on Vulcan and putting T'Pau into power over a government that wants to end the alliance now that the immediate threat has been dealt with - a regime similar to the dissidents in TNG: Gambit
) "and the galaxy would be in turmoil, which means that the Federation was founded on a lie. But is it better to live in a galaxy which is fractured or a galaxy which is united by such shady dealings? There's potential here for morality questions which go above and beyond what the Dominion War or Xindi arc was capable of because it is redefining our understanding of the entire Star Trek universe."
As for how I would make it look more primitive while still pleasing modern sensiblities.... I think ENT did a very job of that as it was.