Is it normal to get sad over a dead spider?

I saw a spider one week ago in the bathroom of my house. He was tiny and looked harmless and he was hiding out under the mirror when he saw me. At first I wanted to kill him, and I waited to see if he moved while I was in the bathroom, but he stayed perfectly still, almost like he was scared of me. I would come back and find him in different places under the bathroom mirror, but he always stayed perfectly still when I opened the door and turned on the light. He was moving around but he was always doing it in the dark. After a while he became like a pet or even a friend to me. I would check up on him to make sure he was all right. A few days ago I saw that he had caught a little fly in his web and I was really happy for him. But this morning my mom cleaned the bathroom and she killed the spider too. I was sad and almost cried when I went into the bathroom and couldn't find him anywhere. I just kept thinking that he was totally innocent and never hurt anyone and that he didn't deserve to die like he was nothing. I was thinking that he probably had friends and family and they would all miss him and it was so terrible that he was gone. And I know it's wrong to think this way but I couldn't help but feel that my life isn't any more important and valuable than his was.