You know what? I kind of wish there were a human on furry game like this. Don't get me wrong, I have no issues with being a furry or whatsoever, but I just can't relate to being an anthropomorphic mouse or dog man balls deep in some hot furry babes. Personally? I think it's the ears. I think I'd be able to relate to a monkey dude in one of these if that ever happens though.
In this case I think the devs are just catering to an assumption that most people just want anthro x anthro by default.
Back in the late 90s/early 00s a bunch of unironic misanthropes joined the fandom and basically made this whole air of anti-human hatred run through it.
Nowadays it's less about that and more the fact that a lot of furry artist just can't really draw human faces as well as anthros. Occasionally there's some furries that have very specific canons and insist they can't simply add humans to their settings, or they think humans are boring compared to male anthros.
In this game's case, it already has an episodic system, so I don't see why it couldn't have an episode with a human guy.
Could always ask them on itch.io or Steam, no harm in asking politely.
EDIT: Since I'm a weirdo that likes to research this stuff, I went and looked at itch.io and the steam discussion page for the game.
They were asked a grand total of once in the steam discussion for the second game if they'd add a human and said "no plans as of now."
That's usually dev speak for "No." but I also think that perhaps just no one really cares with this game. I mean it IS called "Sex and The Furry Titty" Not "Sex and The Furry Titty And This Human Dude We Added Because Someone With A Halo Reach Avatar Asked Us In 2023"
You could probably ask them again, maybe mentioning their previous answer to Halo man and saying if it's more a lack of support of the idea, a worry about alienating fans, or an ideology issue. Alternatively if you pay for the max Patreon tier, you apparently get "direct access" to a private discord channel to talk to the devs. I would heavily advise against doing this though, because it sounds like a great way to spend 80-100 dollars just to be flat out told "No" like you're rocking a Noble 6 avatar. And if I wanted to do that, I'd be on Tinder, not F95.