Admittedly, this is less of a rambling, and more of a sharing of sites that may help clarify things. Back when I first found myself, there were a lot more resources for dragonkin(and other otherkin) but a lot have faded from public view, or been lost, over the years. A few are still around, and I thought I'd highlight some of those, as they are far better at tackling this topic than I.
Baxil's site was one of the first informative resources I found when trying to find more information about this myself. It tries to stay fairly neutral, and may be enlightening, but ti also has not been updated in years so it doesn't touch on later developments, like how therian and otherkin have kind of coalesced into a single concept in the modern communities.
Theri There is a webcomic meant to help cast a (sometimes humorous) informative light on what exactly the otherkin experience is like, as well as highlight just how many different ways there are to experience it. If you're new to all this, I'd highly recommend reading through it, to get a visceral grasp of what it means.
Jafira is another dragon who's been around longer than I have and seen much, and she's written quite a book on the whole thing. Where Baxil's FAQ is brief, this goes a lot deeper, and is also more recent as well. If the above hasn't given you a clear idea, or you're curious for more, give it a read!
One of the few dragonkin communities still alive and kicking these days. There is a forum and Discord, but there also is a bit of vetting process for both, for obvious reasons.
Personal FAQ
There are a few further points however I feel are still worth addressing, as they relate to more recent developments than any of the above, or are things I think are of definitely importance to at least cover myself.
From the outside looking in, I'm sure furry and otherkin seem to basically be the same thing, just otherkin take it much farther.In a way, they're right, but also not.
With furry, it's more like roleplaying a character. You've created a representation of yourself- like putting on a Halloween mask. You still may visualize yourself as human if everything was stripped away, and the 'sona is something you can leave behind at any time.
With otherkin, you're not putting on a mask - you're effectively taking it off. You're saying that if everything was stripped away except your core essence, your soul, this is the form it would take. It's not a representation - it IS you, and not a form you can easily put down, if at all.
The best way I've seen it put: "If your fursona is closer to being "you" than a "representation of you", that might not just be your fursona"
The short version: at one time, therian was reserved for those identifying as natural Terran species, and otherkin was meant for those of a more mythological persuasion. With some communities taking the otherkin label and running it far away from its original meanings and intentions, therian has been adopted among dragons, gryphons, and the like as a term without quite the same modern baggage. In truth, they were always kind of the same thing, but now they're used interchangably pretty much, from what I've seen of the wider community.
Alterhuman is a more recent term I've come across, that basically describes the same sorts of folk as us. It's mean to acknowledge our human aspects(and again, we are running on human hardware in this life, and claiming otherwise is not being truthful with yourself) while also emphasizing our alter nate natures. It also includes more humanoid beings, such as lamias, while therian tends to be more used with us more beast-like beings. There may be some other nuance I am missing, but for general purposes I'd consider it a good catchall term for all types of therian and otherkin.
The "delta theta" symbol (as it's called) comes from the therian side of the community, as a way to denote their status to those in the know. It was originally developed among the werewolf community, with delta relating to change, and theta being a referance to therians. With the blending of the two communities I mentioned above, its been showing up more often among 'kin as well. The otherkin community had previously semi-adopted the seven-pointed star from the elven otherkin(who are vanishingly rare to encounter these days to my understanding) so that will sometimes get combined in as well.
Yes and no. Faith unquestioned and reaffirmed is not faith, and in the same way identity unexamined is not identity. This is a belief that is definitely seems out there compared to other, more mainstream beliefs, but those that truly are alterhuman after taking a good, hard look at ourselves, will be unable to deny it. Self-criticism and self-examination may be hard, but it is crucial in my opinion, especially early on, when you're new to this and it's all bright and shiny and everything is exciting an there's a whole new world you haven't seen before. When you've just discovered the possibility of something like this, the allure can cause you to go running off down the wrong road, before you've even determined whether its your road you should be walking or not, and there's no shame in realizing you aren't one in the end! It's not just assuming fancy costume or avatar; it's about looking at your very core and recognizing and acknowledging what you see there. It's self-discovery, and avoiding all just robs yourself of a richer, more meaningful view of yourself and who you truly are.
A word usually used by people to reference that they relate to a being or creature. Despite the nomenclature being the same, it doesn't mean you -are- something in all instances where I've seen it used, just that you see yourself -in- something. Basically the old "X is my spirit animal" trope, but reworded in a way that is less offensive to those who actually have or worship animal spirits. But because it sounds like otherkin and such, people less in the know try to relate the two, and honestly it makes me cringe a bit because of that. Who knows, maybe it'll get redeemed later as the kids take over, but as I said, I have yet to see it used in a way I would consider to actually mean otherkin.
In a nutshell, fictionkin are those who consider themselves to be otherkin of a modern fictional creation. For an example that kind of hit the mainstream, tehre were quite a few people who thought themselves fictionkin of the Navi from the Avatar movie after it first came out. I can't totally gainsay fictionkin without touching on the hypocritical, as after all, isn't myth kind of really old fiction? And thus dragonkin and gryphonkin and the like similar to fictionkin? They all require alternate planets, timelines, or even universes with slightly different laws of physics to happen the way some have past life memories of.
While I can understand fictionkin of fictional species (as, after all they may not be quite that but their kintype may be similar enough that it makes for a close match and an easy label) I draw the line at those who claim to be reincarnations of fictional characters. Yes, this is a thing. Back in Final Fantasy 7's initial heyday, there were those who found their way into the communities who claimed to be reincarnations of Cloud. Or Sephiroth. (Oh BOY was there a lot of Sephiroth.) Many people reincarnating the same soul all at the same time just does not make any kind of sense, even for reincarnation. If I were to try to bullshit an answer, it would either involve multiple timelines all trying to reincarnate here(in which case why would this many Sephiroth happen to reincarnate in our timeline? and why not some of the lesser NPCs?) or a soul fracturing, and if it were to fracture enough times to account for all those sephiroths, the Sephiroth "essence" for lack of a better word would be so diluted it wouldn't matter. That's even assuming that cross-timeline reincarnation is a thing, of course.
Ultimately, I bet if you went back to all those supposed Sephiroths today, none of them are claiming that anymore. It's ultimately people hearing about otherkin in a distorted way and then a combination of wishful thinking and/or deeply relating to a character causing them to come to a wrong conclusion. Like I said, species can make a kind of sense. Characters? Just no.
While I know Jafira did address fictionkin in her document, I figured I may as well cover it as well. Hopefully the links above and my own additions proved enlightening!