-What I've been Saying For years in one form or another-:
Sailor Moon, the story (and Sailor V by extension), has multiple core themes.
Unity is one of them. In fact, after Love and Friendship, it's the Third pillar of the ENTIRE Franchise, but lets stick to the Manga/Crystal version for a second.
Every time Usagi needs a power up or needs to do the Big Damn Moment, guess what happens JUST BEFORE that?
She receives power from her Lover and Friends.
Nearly Every. Single. Time. Even in the Stars Arc.
This is important. It's a recurring theme.
-Friends sacrifice their powers to awaken her inside Metallia, offering their power to her there. As well as Luna praying at the Shrine on the Moon. Mamoru, tho blind and unaware of his own power, ALSO offered up his to support her and brings her back. She gets an upgrade from the palace (newly rebuilt FROM that power.) and revives the world here.
-Not only is she supported by her friends but she's supported by HERSELF as well. The Big Moment of destroying Nemesis happens with her and Mamoru embracing. Chibimoon Arrives to help. They destroy the Phantom there finally. Later, everyone gets an upgrade here. (this is also where Mamoru gets a more active power learning from his future self- Much like Usagi getting her power boost as well)
-Guess what happens here? More Emphasis on Unity. The only way for Super Sailor Moon to even EXIST is for ALL the sailor soldiers to combine their powers. First Sailor Moon/Tuxedo Mask and Chibimoon created the Holy Grail (the vessel in which to contain the powers), the Inners and Outers contribute their powers. And Boom: Super Sailor Moon happens. And she only exists when Everyone Is United in a common Goal. Saturn's Power completes this at the end and is the reason Usagi can revive the land after Pharaoh 90 fucks it up. In addition to releasing the Combing Powers of everyone in the Grail plus the Silver Crystal which Detached the body of the Darkness from the Earth that MADE it possible to Save the Earth in the first place.
-Again. Unity is the Main reason anything actually gets saved. Everything is about them wanting to be together again. Wanting to see each other. Even in individual chapters, we SEE the Inners and Outers actually want to see each other even without referencing Usagi at all. This tells us, in text, they're not all only about Usagi. The friendship is actually between all eleven characters. (Yes, I included Mamoru. Fourteen if you count the cats because they *are* instrumental to the theme and powerups they achieve through that. Ex: Luna and the Shrine from the DK arc. and Artemis to Minako in the Dream Arc).
The only thing the Dream arc does is Reinforce that while they have a main goal dream: Protect the princess and prince and the Earth, they find they can *still* have their own plans and goals which is discussed multiple times throughout the story itself. They never forget their dreams or the things they've achieved while still in service to their destinies.
Side Bar- I think this is what trips people up. People think you're only supposed to have One Goal in life. When you can have multiple. Not only that, multiple dreams CAN coexist as being equally important!
And for whatever reason, people can't reconcile that fact or grasp it because for a long time, socially, we're condition to think you can only have one (1) goal at a time. It's only reachable if it's one. It can only be one goal that's more important than the others.
So seeing the story told and being shown that the Sailor Soldiers have Multiple Dreams/Goals in mind and that for them- yes! Being a Sailor Soldier is fulfilling too! Yes, we take our duty to the one we care about very seriously and are willing to keep that person(s) safe not just because of duty but also deep affection!
But that's not all of who they are. and the Dream Arc lays this out quite matter of fact in the text itself.
(It also probably represents the struggle many teenagers and even adults have with fulfilling their dreams and whether or not they're meant to do a thing. There's a lot of the Inners struggle with these notions. )
Anyway back on track: In Dream Arc, this is where everyone gets their power up/Awaken to a power they didn't have before. It brings the Unity part of the story into focus big time with the Inclusion of Mamoru and Chibiusa finally getting the things they haven't had before.
Mamoru's Sailor Crystal is awakened fully thanks to Usagi.
Chibiusa gets her Team (though it's early for them) and she gets her own Actual Crystal that isn't a copy of her mothers (Pink Moon Crystal with it's own design. (can hatch a bunch of theories on why her's is more flowery than her parents but I digress)
And what do they do with their new powers?
They all give it to Sailor Moon.
They all get their own power ups because their hearts and goals all align.
That's why everyone is Eternal form.
-Hi, It's Unity again but on a Galaxy Wide level.
this is a controversial take but you know what defeats Chaos wasn't *just* Usagi. Usagi was instrumental and she IS the vessel that moves it but guess what she does before that? What everyone Says later when they reunite:
Usagi called for the assistance of Everyone in the Galaxy Cauldron. Meaning Everyone including the Asteroid senshi of the future, gave their power to her.
And I really wish people understood that because it goes back to the first through fourth arcs of the story.
The Story is literally saying you do not need to be alone. You don't have to do the thing by yourself.
This is what Sailor Moon is about.
It's about a girl, yes, but it's also about the bonds she's made with others. How those bonds strengthen her. How, without them, she couldn't have climbed as high as she could. Become the person she was without the people behind her.
That Unity will save a galaxy.
That Unity is not a deterrent nor will it negate your own dreams, but will be a buttress for them.
The thing the Sailor soldiers have built together was a community. They exist with a destiny, yes, but they are Normal people outside of that that will face whatever comes their way.