I don't have the skill or the time to model new ships, so I'd have to regurgitate old creations. Would people still play it with ships they have already seen in other mods?
There are quite a few great campaigns out there that use no new ships at all, or very few (for example, Derelict, Destiny of Peace, Silent Threat: Reborn and Sync), and a few ships have seen a lot of use in campaigns (the Raynor is a common one). There are plenty of ships available on FreeSpaceMods that I have not seen used in a campaign yet, so you have some choice.
I also would be planning a story based Post Capella, which is a territory that a lot of the best mods already cover. I just always wanted my own telling, my own theories, and my own dream missions out there.
There's nothing wrong with some fresh ideas about what happens post Capella.
The ending of FreeSpace 2 allows for a lot of creativity.
I have a different take on what happened after the second shivan invasion, would that make me wrong if its not the same as Blue Planet or Inferno?
Certainly not. The very fact that Blue Planet and Inferno are (very good, of course) fan-made campaigns means that they hold no claim to being the "correct" post Capella campaign. Both of these campaigns have a different take on the post Capella era, anyway.
But what I've always been told is that 'Story is King', regardless of what flashy effects you can put in a game.
Perfectly true, see the first point. However, you don't have to do too much character development if it's not important to the story you want to tell - for example, The Aeos Affair is another very good campaign, with a good story and - challenging, admittedly, but good - gameplay, but with hardly (if any) character development. Heck, the original FreeSpace 2 campaign only really developed the characters of Snipes and Bosch.
does the freespace community still look for and accept new campaigns?
The community always likes new campaigns. I mean, there's no shortage of new projects having just been released or announced, and you usually have a lot of people looking forward to a new story, no matter what the era - from the Ancient-Shivan War (ASW, obviously), to before the Terran-Vasudan War (Syrk, The Unification War), to the Reconstruction period (Rogues!, Homesick), to other parts of the Second Shivan Incursion (The Aeos Affair, Vassago's Dirge).
So, to answer your original question - if you've got some story ideas, time, and the motivation to make them into reality (well, to put them into FRED, anyway
). One tip, though - start out small. Just try your hand at doing some stand-alone missions first, or a mini-campaign of a maybe four-eight missions. Once you've had some experience in making missions, you can try to make a bigger one if you want. And you're always welcome to ask for help here on FREDding, tabiling or other stuff like that.