I have a 5.5 inch rainbow shark and it isn't aggressive to any of my fish, not the angels, not the 3 inch emerald Cory, not even the 1 inch bronze cory. The most he does is chase other fish away from his favorite flower pot cave. I may just have a peaceful one, I don't know.
Anyway, your stocking looks good except for the rainbow shark. I'd rehome him like others have said so far. If you got rid of him, I'd say you could have 15 neons.
Do you have any plans to make it a planted tank?
If you need some beginner plants, I suggest anubias. They are a rather hardy species and easy to grow species in my experience. Anubias Nana is a personal favorite of mine. If you want something extra tiny, look up anubias petiete. If you're looking for something the complete opposite of the extra tiny anubias petiete, try the huge amazon sword. Swords are hardy in general. Want something that can spread fasts and looks nice? Try crypts. There are so many different types of crypts that you could fill a 55 gallon or even a 75 gallon with different types of crypts.
Hear me out on this one, look into bamboo...... They can make the tank a true centerpiece and eye catcher in the room. But you have to get them pretty tall, tall enough that the leaves stick out of the water. I personally bought 12 sticks of bamboo that had 24 inch straight stalks. With the curvy parts and the leaves, it comes to 40 inches. I bought mine on amazon, so if you do get some, get the 24 inch ones as they will be plenty tall enough.
It'll be a nice attention piece if you entertain a lot.
(When I just went to measure my bamboo. I found a mystery snail egg clutch on it
)