I honestly hadn’t even considered it. I didn’t even know creators could be kin of their own works…

I would definitely take some time and consider it. 

You absolutely can be kin of your own work. I don’t have any data on how common it is, but it seems fairly prevalent. 

Depending on the ‘content’ of the work, you might fall more into otherkin than fictionkin. (If its dragons, or if its college students).

Search yourself and do some reflecting. Do these works and these worlds ring ‘true’ for you? Are they people you knew? Someone you were? Is it home? Don’t be too quick to think that its impossible. Your inspiration and creativity for these worlds may spring from something that was true.