Fish do indeed feel pain when hooked as fish do have nerve endings also known as nociceptors in their mouths and lips that react to the tissue damage from a hook.
And when a fish is hooked, the fish do exhibit physiological distress like rubbing their mouths, refusing to eat and even altering of their swimming behavior.
If you want to reduce the pain that the fish experiences when hooked, especially when doing catch and release fishing, you can instead use barbless hooks, which are hooks that are easier to remove and cause much less tissue damage.
Also you can keep the fish in water as much as possible or handle the fish with wet hands to protect the fish's slime coat and act quickly when removing the hook to minimize the time the fish is out of it's environment and has the hook in it's mouth.
Fish are also able to see you on the bank as fish eyes are located on the sides of the fish's heads and fish have a massive field of view or vision, which is up to 360 degrees.
Due to the fish's excellent and massive field of vision that is up to 360 degrees the fish can easily spot shadows and movement outside of the water, including on the bank.
Fish can see you through the "Snell's Window" Effect and distance.
When it comes to the "Snell's Window" Effect, due to the way the light bends (refracts) in the water, the fish can actually see you even when you're sitting far back from the water's edge.
The fish look up through a cone shaped window in the water's surface and see a distorted panoramic view of the sky, the trees and yourself and others.
Most freshwater fish are also near sighted and can see around 15 feet in front of them with great clarity.
Although if the water is clear and calm, the fish can also easily spot a human that is standing high on a bank from further away.
To avoid the fish seeing you and help yourself remain hidden when fishing, watch your silhouette and avoid standing directly on the skyline or on the edge of the bank, as it creates a highly visible silhouette of yourself.
And wear earth toned colored clothes, as bright colored clothing creates a stark contrast against the natural background, wear greens, browns or camo to blend in.
And avoid making any sudden movements, as any quick, jerky movements will spook fish much faster than simply remaining standing still.
You can also use natural cover, like trees, bushes, or tall grass along the shoreline to break up your profile.
Also making noises and talking too loud can even spook fish, so you need to remain somewhat quiet, although talking in normal volume is okay.
Fish can hear sounds, but they can't hear the specifics of your conversation, and so having a casual conversation won't send the fish fleeing in terror, but making any loud or sudden noises will spook fish.