I think you mixed things a little bit. Where does ruby (the language) uses "convention over configuration"? I see frameworks using this but not the language itself. If you dont like ruby on rails, thats fine, I dont like either. But that has nothing to do with the language itself.
When you talk about "functions are not first class objects", do you mean you cannot assign it to a var? Well thats because they are not functions, they are methods. I think thats great. A method belongs to a class. Thats how Smalltalk also implemented it, as far as I know. In fact Ruby and smalltalk (the mother of all OO languages) shares a lot in common.
If you like functional programming style, thats fine, but yeah then maybe you should use haskell, erlang, elixir, ...
When you talk about "functions are not first class objects", do you mean you cannot assign it to a var? Well thats because they are not functions, they are methods. I think thats great. A method belongs to a class. Thats how Smalltalk also implemented it, as far as I know. In fact Ruby and smalltalk (the mother of all OO languages) shares a lot in common.
If you like functional programming style, thats fine, but yeah then maybe you should use haskell, erlang, elixir, ...