@Stephanie2079 Yes, be very clear about the situation in your listing description. That guests will be sharing the common spaces with you and your parents, who are temporarily living in your other spare room, and that the bathroom will be shared with your parents.
When that situation changes, you just go back and edit your listing. And if it changes after you already have bookings, then just let the upcoming guests know in what way it has changed. Or if your folks will likely be leaving soon, just do as you're doing and explain in messaging.
Honestly, I have never found that my guests had expectations beyond what was offered in my ad, although YMMV. As I mentioned, just be yourself, don't think you have to act some certain way as a host- that would be stressful. It's your home, and while you need to be a little tolerant, it's the guest who needs to fit into your lifestyle in a homeshare situation.
Some guests will be chatty and friendly, and want to hang out a bit with you, some will even end up feeling like you've known them a long time, some will be more private. Just establish your boundaries. You don't want someone laying about on the living room couch all day, sluglike, or leaving their personal belongings strewn all over, cluttering up common shared space. Nor ones who think all you have to do all day is sit around and chat with them and monopolize your time.
But the flip side of that is you also don't want guests who just hole up in their room all day, scurrying out to use the bathroom or the kitchen, and then hiding away again, because that can feel weird, like you're living with some phantom presence.
There's guests I've spent lots of good times with, laughing hysterically about something over a bottle of wine, and some I barely see- they're out and about a lot,and tend to stay in their room when home. But even the more private ones have been perfectly pleasant when we cross paths.
You may also get guests who seem a bit strange, but may be on the autism spectrum. I've had a couple of those I suspected were in that category. Not unfriendly, but obviously rather uncomfortable with social interaction. So don't take that sort of thing personally. You'd think they wouldn't book home shares, but some do.
I find that exchanging several messages with guests, part information you need to convey, and part just establishing some kind of rapport, even some humor, gives you an idea of who you are going to be dealing with, and keeps things from feeling awkward when they arrive.