Is 17F sending her photos to boys normal?

(TLDR at the end)
Hey! I mostly don't use online messengers, not even whatsapp, as I meet my friends, family and acquaintances irl. But I started speaking to a girl (17F, have to mention to get any comments. Me-17M) of other batch time whom I meet once in some days. So, I had taken her number to send her a book's pdf. Then didn't meet or message her as our work was done.
A few days later, she messaged me casually and we started to talk on whatsapp. Once, we were talking about photos and she sent me some of her photos, which I replied that they are good. I thought that it is due to the conversation or maybe because we were too friendly or my friends say she might like me.

Later when we met, I told her that she chats a lot and has many contacts from her old school on her phone while I mostly stopped talking to my school friends after 10th. Then, she showed me her contacts with whom she talks, mostly girls from her class. Then, I saw that she had sent a selfie to another boy also. We continued to talk on other topics. So, I want to ask is this normal?
Also, to me it seemed that this boy probably likes her but she doesn't. She doesn't think that he likes her and is just a friend and I didn't mention that I think he does as we boys know that's the case most of the times (but good if it's not here). So why would she do that? Is this for validation?

TLDR: Do girls send their photos to boys normally? I am unaware as I don't use online messengers much.