I found out I was someone’s “backup option” after they got rejected

I started talking to someone a few weeks ago. Things were going well. Good conversations, regular texting, even made plans to meet. Then recently, I found out something through a mutual friend. Apparently, before talking to me, they were really interested in someone else… and got rejected. And right after that, they started talking to me. Now I can’t look at anything the same way. Every message feels different. Every “I like talking to you” feels… less real. I don’t know if I’m overreacting. Because technically, they didn’t do anything wrong. We weren’t committed or anything. But it still feels like I was the second option. And I don’t know if I should continue or just walk away now.