Welcome to the site! These guys have given you some great advise, which they always do!
Fly tying is a passion of mine. I enjoy experimenting with many types of flies, and have found that most flies will catch some fish.
The majority of the fishing I do is for warmwater & tidalwater species, just as you're doing. This is generally not finesse fishing. With the exception of panfish, I like big flies most of the time and I use some older, been around a long time & have been productive type patterns such as Deceivers, Seaducers, Clousers, etc. These are all general purpose styles that can work on a variety of species & in various situations or conditions. I'll also use flies that are more specific to the area, such as crab or shrimp patterns for Redfish or Eel patterns for Stripers. This approach has served me very well for many, many years.
However, the fly is only part of the solution. Location of where you cast the fly & presentation is usually a much more important part. You may be walking up & casting and catching a few fish, but it's likely if you spent a little extra time observing & casting with a purpose, you might have more success. This is something I learned very early in my fly fishing experience. I also learned to make each cast count. I'm also self taught, and in my early years struggled with casting & accuracy. It's one thing to cast the fly, it's another to do it in a manner that doesn't spook the fish, or alert them that somethings not as it should be. Every cast I make, I have a target to hit, even when "blind" casting & searching for fish. Doesn't always work out that I hit my target. Wind or waves can create issues, but I never cast blindly!
60 ft casts are great, but it's often more productive to work the water closer to you first, then work out to greater distance. You may be missing a lot of fish if you're just firing off long distance casts with no regard to what might be lurking nearby. Week before last, I caught a nice Redfish that was within 15 ft of me, that I didn't even know was there at first. I saw a clue that indicated the fish was there & made a cast. Actually more of a flip, but this is fly fishing!
I had been watching another Red that never got close enough for an accurate cast. Distance casting is great if you can do it, but not always the best approach or necessary.
Also, stealth can be important. Any place that gets fishing pressure, and the fish see anglers casting various flies or lures, they're going to get wary to an extent. Fish rely on instincts, and if they know you're there, their instincts tell them to be cautious, particularly the bigger they get. In my above scenario, I was standing on a grass flat, waiting for fish to show themselves. I saw plenty, but they would often get close to me before I saw them. I stood very still, made minimal movements & paid attention to what was going on around me. Even then, I didn't see everything! I spooked a few fish with casts too!
The final advise I'll give is to be patient. Any place I go to fish, I spend some time looking & observing before I make my first cast. Often, I might see something that indicates where a potential target may be. I then approach my first cast & each subsequent cast as a hunter stalking his target and I mentally plan how best to present the fly. Sometimes this entire process only takes a few minutes, sometimes much longer, but it's well worth the patience of doing so, as for me it's resulted in more & bigger fish caught & landed.
Take the advise the others have given & get some flies that cover different situations (topwater, shallow, mid depth, deep, and various sink rates) & get some good local advise. Variety for flies to have on hand is always a good idea. Then apply that advise to what I've just said & you may find that you'll catch more fish regardless of what you may be targeting.