So yea. What had happened was…

I’ve told this guy that I like him (I’ll refer to him as R), and he’s told me that he likes me too. He aren’t really going out yet (nobody’s asked anyone out yet) but that’s not my immediate point. The day before he told me he liked me, he stated that he was giving up on a guy he liked but didn’t like him back. I get the slight feeling that I might be something of a rebound, or that he’s just “settling” for me. Like “well, I can’t go out w/ -----, so I’ll just go out w/ Mike.”

I thought about this, and then I realized that I don’t really care overmuch if he’s just settling for me.

I’m not even entirely sure if I should care. That’s my main question. Does it really make a difference if I wasn’t his first choice?

To me, guys have trouble stating the fact that they do want to date.
My guess is to play it out. Maybe you two will grow into something he never had with the guy before? I don't think your the next person on the "list". If he is a whore then maybe so.
And if things don't work out as planned, well you're not married! Have fun with your life! You only get one!

This could go both ways, you could one in fact tell him that you don't want to be his rebound and ask him if you are. Or you could just keep moving on with this and see if you are in fact the rebound and not care or care. i've been a sort of rebound before in like the 7th grade but now my girlfriend and I have been dating since.
hope this helps you at all.