Your level isn't too bad. Watching from the video, it seems fairly fun to play and the difficulty seems pretty far. However, it's pretty a level without salt. There's nothing really new there. You didn't change or mix the graphics or design something new -- it's pretty much a level that Nintendo could have designed in Super Mario World.
So if you want to make something more different, unique and appealing, I'd suggest you actually thinking: "what kind of level I could do that it's at same time fun and unique?" "what enemies combination should I use to make my level with a different feel?" "what can I merge from GFX00 to GFX31 and create a completely new atmosphere from the SMW?". These kind of questions helps to you analyze what you can and should do in your level. You still have lot of time left to improve it, so don't get sad! I believe you can make a pretty cool if you take more effort in the design and appealing aspects.
And in case you're in doubt in what to do, just look the other threads there and get some inspiration. Of course, feel free to ask in the forums in case you're in doubt if some graphical mix, for example, is allowed.
- SnesLab Discord