I don't feel attracted to anybody at all, but I look them up and down. Is this normal? I'm scared to tell anybody in real life so I'm asking here instead. Can anybody help Me?

It is perfectly normal. I felt that way too, before realising I was asexual. I realised I basically admired people the way I looked at a flower, if that makes sense.

If you don't look at people because of sexual attraction but simply out of curiosity or aesthetic appreciation, chances are that you are asexual, and that's a perfectly normal and valid identity. It's ok to feel a bit confused, just take your time to come to terms with it, try talking to other asexual people if you have the chance, and when you'll be more familiar and comfortable with your identity, you can consider sharing it with people in you real life.