A guy I don't know replied to my Instagram story, what does it mean?

I don't know this guy but he recently followed me on instagram about 2 weeks ago and I followed him back because he looked nice. I noticed that he is following a lot of girls daily, and he likes their pictures as well. I rarely post pictures on instagram, but I do post stories, and he is always the first to watch them.
Today he responded to one of them after a few minutes that I posted it. We had a really short 10 minute conversation but I'm still confused as to why did he reply to my story.
Is he interested in me? Or do you think that he does this to every girl that he follows?
He is interested in you
He does that to every girl
Other (please explain)
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It wasn't even a picture of me that I posted on the story, it was more of what I was doing at that time.
A guy I don't know replied to my Instagram story, what does it mean?
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