Is the kick drum panned to the left? That's kind of odd, but obviously your choice! The biggest things I'd change right away:
Bass is too loud in the mids: is that direct-in? It sounds like it needs to be put through an amp, or at least a decent amp sim to get that low-end and higher-end grit. Also turn it down a bit.
Guitars are too quiet for my taste, and a little too panned: try 65-75% each. Also take out most of that reverb you have on 'em (assuming it's artificial)
Vocals either have too much reverb, or you captured too much of the smallish room you were in: either way, there's too much, and it sounds too small.
The drummer either didn't hit nearly hard enough, had a mediocre kit, or you didn't close-mic the snare. Either way, I'm not sure there's much you can do. The double-kick doesn't make any sense for that part towards the end if you ask me hah
The guitar solo sounds REALLY odd, is that an amp sim? It sounds like the guy in contra is playing a guitar solo through the 4-bit nintendo!
Levels-wise, most everything is pretty good considering your source material! Definitely way good enough for a simple demo to hand out at shows
It captures the song well, and represents the band accurately. The biggest thing I'd say is just learn from your experience, make notes, and improve the things you don't like. Keep doing this, keep recording, and things will keep improving dramatically!
*edit: I just noticed you said your mains were clipping with any more volume on the kick/snare: try taking out more of the kick's lower-mids, then throwing both of them through a compressor.