Is it weird that I'm still attracted to guys who aren't alpha males?

The concept of the alpha male is actually more mythology than fact. To protect and provide are generally masculine traits. "Alpha males" tend to be domineering assholes and typically aren't good at either of those roles.

How about an old alpha male that's still fighting for dominance of the females ?

The "alpha male" types and wannabe alpha types take the longest to grow up and stop being a-holes...this doesn't mean that effeminism is good either, but yeah...you know what I mean..

It makes sense to be attracted to the modern equivalent to the alpha male; brains can provide more security than muscles in a modern society.

No, not everyone like s assholes.