I can't tell you why you don't like your landscapes, but I can tell you what I see in this image. Firstly, remember that we live in a complex and chaotic world. As photographers, we cannot add to a scene, but we can reduce it and simplify it. The world is actually a jumbled mess that our brains are extremely good at filtering and deciding what is important. However, when we transfer the world onto the 2D surface of an image, we lose that ability to filter the environment in real time. Our goal is to take a complex scene in which the elements may clash and simplify it to a strong composition.
Let's take a look at your image. The first question is what attracted you to this scene. What did you want to photograph? Was it the bridge? In this scene, there are several competing elements: the tree on the left, the tree behind the bridge, the railing and path behind the bridge, and the cars in the parking lot. As you can see, there are multiple elements in this photograph that do not work together to make the composition stronger but instead interfere with each other, weakening the composition. Simply being able to analyze an image and suggesting how to make it stronger is easy in comparison to actually carrying out that task.
If I were personally trying to shoot this scene (I probably would have not shot this scene and moved on due to its complexity), I would attempt to position my camera in such a way as to focus on the subject and remove as much distraction as possible. This process requires trying several different camera positions and compositions. For example, try getting really close to the bridge and shooting with a wide angle, emphasizing the structure of the bridge and the leaves at its base. When I shoot a landscape, I visualize the shot I want and try several different compositions, refining the image continuously. In a nutshell, I approach composition in this way.
The next issue to address is the lighting of the scene. This scene appears to be photographed with overcast light. Different scenes call for different lighting scenarios. Overcast light is flat and dull, and at times, is what is called for. In this scenario, I do not think that the light is helping you. It makes the scene dull, flat, and unexciting. Golden hour light is the most dynamic light for landscape photography. Not only are the weather conditions important, but the direction of light is also key. I would have likely approached this image at a different time of day or under different lighting conditions.
The concepts that I have mentioned here are only a few of many that need to be considered with landscape photography. If you would like to improve your landscapes, I suggest that you study landscapes and identify the elements that make you like them. Good landscape photography requires experience behind the camera, so I suggest that you continue shooting if you would like to improve. I hope you find these suggestions helpful.