You have some good shots.
A: Stretch your camera to the limit. Snag what apps there are. Start here: https://forums.oneplus.net/threads/full-oneplus-one-camera-guide-including-third-party-apps.278496/
B: Recognize that certain situations aren’t going to work well. Shots like the chess board with a blob of coffee cup in the corner, and blurry distance. Doesn’t mean the whole picture has to be in focus, but chose your out of focus elements.
C: The bridge turns into a silhouette because your camera thinks that the world is grey. If most of your shot is bright sky, then everything else will be too dark. Move your point of view to the point where there is less sky. This will also be a problem with snowscapes, and maybe beaches with light sand and too much sun.
D: The opposite holds true too. Too much dark stuff, and the light stuff gets washed out. You’re in the right part of the world for your camera. Overcast days will often have very vivid colours, and won’t wash out or turn to ink.
I like the stair shot, but what is the red thing? Ambiguity is ok.
Google Street photography. I think you and your phone would have fun.
Good cameras don’t have to cost the earth. Both Nikon and Canon have a variety of cameras. Often paying twice the price gives you a few more features, and translates into a few percent more situations where you can get a good pic.
You can often pick up what was really hot 4 years ago for a song. When you are ready for that, read up on them. Lot to soak up.
If your school has a school paper, consider joining the staff as a photographer. Often they have a couple clunker cameras you can use. Or you may do it with your phone.
Few people make their living taking pictures. Most of those have a narrow routine of weddings and portraits. But there is no reason not to enjoy creating and sharing beauty.