Lyric discussion by Farenyth 

Cover art for Gila lyrics by Beach House

Since I think it will be really difficult to come to a conclusion on the meaning, I'm just going to give the concept I gained from it.

I take the song to be much more specific, rather than abstract or general.

"Man, you got a lot of jokes to tell / So you throw your baby’s banners down the well"

In context with the other lines made me imagine a previous, yesteryear lover toying with the affection of the author while this lover is already taken from her physically or emotionally by others.

"Sure, you’ve got a handle on the past / It’s why you keep your little lovers in your lap" Support for the idea that it refers to a long time lover with his handle on the past, and that he has multiple lovers like him he plays with.

"Hoping for the last ship to arrive I’ve been blessed with a kingdom, half-mine" I took the kingdom to see his, or perhaps his emotions, half to her and half to someone else. The ship being her being the last "ship" to land in his kingdom.

Just a shot at it.

My shake at it:

He is an aging player. She wants to have a family with him, he does not wish to commit to such a "binding" situation - he is too busy socializing.

His socializing as a priority is reflected in, "Man you got a lot of jokes to tell, So, you throw your baby's banners down the well"(i.e. she is joking on his commitment to social engagement over what she deems as a more lasting "family" future they can have together)

His "handle on the past" is indirectly a statement...