I would say you need to develop your sense of composition and the best way to start with is to pay attention to formal aspects - main focus of attention, lines of vision, visional weight, perspective, balance of spaces and subjects and of course the light - highlights, shadows and everything in between. Try to find scenes with well coordinated colors, good foreground, mid and background to add depth and put the viewers into your scenes.
Your street pictures are OK, and unlike Derrel I have absolutely nothing against exclusively shooting horizontals. Some street shooters never shoot verticals and the reason is street is in many ways a horizonltal thing. Verticals are good for portraits, street needs context and context demands horizontals. So if that is is your style then it is absolutely fine.
But at the moment your street shots are a bit messy and lacking focus. I am not talking about sharpness, screw sharpness, you need focus of attention in your shots, not just a crowd of people. Pay more attention to clearer compositions, start with simple ones and gradually make it more complicated and interesting. I think you have potential.
Agree about watermarks, they are meaningless and their only purpose is to ruin the image.