Why does "I love" translate to "Я люблю", whereas "I like" doesn't use the Russian "я" for "I"?

Saying that you "like" something in Russian uses a different structure to saying that you "love" something (я люблю). You would use мне нравится to mean "I like" and that literally translates to "...appeals to me". Мне is the first person pronoun "I" (or я) in the dative case, i.e. "to me", and нравится means "to appeal to" or "to be liked by". However, нравится is a verb, therefore it must decline according to the subject of the sentence, i.e. what appeals to you (what you like). If it is one thing that you like, e.g. a book, it is мне нравится книга, where нравится is used for the singular. Therefore, if you like more than one book (the books), then нравится would change to нравятся - мне нравятся книги (I like the books).