Right now I've done this as this one is the player's ship.

Honestly, it just looks like a flat triangle with another flat blue triangle inside it.  I'd look at references of some SHMUP games you enjoy for inspiration on how to make an appealing spaceship.  Even if you look at something as simple as Galaga; it's very simplistic, but the shape of the player's ship is enough to make you realize it's a ship of some sort.  No offense, but when I look at your ship all I see is a triangle of sorts.  So if you're going to stick with such a symbolic style then you're going to have to make sure you exaggerate parts of the ship like engines, gun turrets, etc. since when it comes to symbolism (at least in this case) shapes are everything, and having a triangle with no recognizeable "spaceship" features will make it just read... as a triangle :P