Am I just overthinking it?
I bet that you've RP'd a lot of things you've never experienced. I've never casted magic, or been on a space ship, been arrested, or had a threesome, or... you get the idea. I mean, how do you roleplay someone else when you're only You? You use your imagination.
You don't have to be perfect at it, just have fun! Try new things.
I prefer non-humans, both as and opposite; I'm a human every day, give me a vacation from that normal. So I guess I'm a xenophile, that non-humanness is aesthetically hot, and the idea of having a different physiology, new appendages etc, to be cool. My main experience and preference is
for anthros. Besides the aesthetics/the fact they "feel" different, I find it useful in that it expands my writing toolkit. Ears/tails make for emotional expression. Different species stereotypes help with personality--the bratty, teasing cat, the quiet and careful mouse, etc. Smell can be played with, along with heightened senses (better hearing, night vision, etc), different physical elements (knotted cocks for instance, alsoo going inot heat). Does it impact behavior--do the cats still kiss or do they instead nuzzle faces, etc. Predator/prey is something that can be easily tossed into anything for that nice fear=arousal instinct, also things like sexy biting is more natural. There's practical applications--cars have to accommodate antlers/horns--as well as cultural, since dogs and cats can't interbreed that's going to have a big impact culturally.
All of that are tools that
can be used but doesn't
have to be; as said earlier, it's a matter of how far non-human you want to go. But also, if you find yourself backsliding into writing them as human in a funny costume--well, that's okay. You don't
need that non-humanness in your face all the time. Explore and play with the parts you like, and don't worry about doing it "wrong"".
Lastly, this is purely a technical thing, but I like the fact that "The species" is a useful way to refer to a character in a paragraph. If you have humans it's usually "Character name" and "he/she". When y ou're writing same sex scenes, that can make being clear who you're talking about really difficult. By saying "the fox" it helps clariy who is doing what to who..