How can I be sure I like someone?

Im 18 years old and have never been in a relationship before, I've never kissed anyone before and never had anything going on with a person beyond platonic interactions. I am someone that struggles figuring out wether I'm interested in someone or not because I don't rlly know what this type of love must feel like.

I am scared that I might not have a crush on someone after acting out on it, only liking the idea of them. But I'm also scared of leaving a chance behind of being with someone I geniunly am interested in.

Here's the thing, there's this guy in my class that I talk to sometimes, we also have the same way home and we always walk together when we can (it's not smth we discussed, it just happened randomly b3cause we don't wanna go alone). We have a lot in common and we have nice conversations. He is sometimes a little bit socially awkward so I don't know whether he feels pressured walking with me or if he geniunly likes it.

He is nice and I am somewhat attracted to him, but it wouldn't mean the end for me if he didn't feel the same way. If he'd ask me out I'd say yes, if not then oh well. There aren't strong feelings attached to him, I just like him like that, that's it.

Is this a crush already or not? And should I maybe act on it? Like I said he doesn't rlly talk to a lot of people at school so I'm a little surprised he opens up pretty quickly when talking to me, on the other hand he always sits down behind me and never next to me in class.

I'm more of an extroverted person so I talk to nearly everyone in my class, he just never clings in to talk as well which leaves me a bit frustrated on how to get closer to him. He seems very shy when we're in a group, but alone it's way easier. He never reaches out on his own tho so I'm left confused on what his feelings are.

I'm just so frustrated and finally take action in my love life :(