New to Photography - is it me or the lense?

Hey everyone, I hope this is okay to post this here. I need your help. I bought a Canon T6i (aka: 750d) a few months ago with the stock EF-S 18-55mm f/3.5-5.6 IS STM lense (Purpose was home video and photo + learn the ropes of photography because I've always had an interest). I've been taking a few shots here and there, using it for (home) video and trying to understand this whole photography thing. I read the first few chapters of Understanding Exposure by Brian Peterson until I understood the triangle and I stopped reading once I learned how to use the settings to get the effect I needed. Also, I read the Canon manual. I've watched some YouTube videos about shutter, exposure and lenses. So I know a little but not a lot about photography.

To my question: Why do my shots look cheap, or just not nice in general? Is it the lighting? Is it my stock lense? Do I need a prime or a wide angle? Is it that the stock lense is limited, or is it that I'm not up to par yet?

If it is me, do I need to take more photos and edit them, read more books, look more at other photographers work? Maybe I still don't understand my camera or cameras in general?

Just looking for a direction. I know that people with skill can use any tool to achieve great things but how can I feel confident I'm growing that skill properly?

Thanks everyone