you took what is essentially a 30-second loop and made a 5:15 arrangement without changing tonality, tempo, style, or significantly changing your chosen instrumentation throughout, and it isn't terribly boring. bravo. this is a stellar attempt that only falls a little short.
from the arrangement side, as others have noted, there's just too many times that you say the same thing. your attempts to mix up the instruments carrying the melody are notable, but there's only so many instruments that can carry it, and you exhausted them by halfway through. so, my suggestion is to explore other historical forms of variations. your arrangement uses some standard theme and variation forms - it's not quite a passacaglia since the bassline never really changes, but you use some of the concepts. my suggestions here are to explore some of the other historical techniques - things like changing or modifying the tonality of a section (Ive's "Variations on America"), dynamic variation (Ron Nelson's "Passacaglia on B-A-C-H" is essentially a 9-minute crescendo), or significant and systemic rhythmic variation (Mozart's "Twelve Variations on 'Ah vous dirai-je, Maman'" - Twinkle Twinkle Little Star!) really can help with taking something that feels samey and turning it on its head. as an example only and not a suggestion, i guarantee that exploring some modal harmonies - even the relative minor! - would really quickly spice up and allow a return to major (and a recap of the initial theme) to hold more water without feeling repetitious.
from a mastering side, i echo nuts in that it's simply too quiet. now, yes, i did just say that significant dynamic contrast can be good - but, this track screams for compression. well-sampled instruments that are properly velocitized can be slammed with compression and still sound like they have dynamic contrast due to the natural changes to the instrument's timbre that occurs when it's played louder. i'm not asking for some huge punchy compressor to bang the crap out of your bassline, but proper compression can really breath some life into the opening and middle sections that are quieter without altering the delicate balance you're trying to create.
this is a real good effort, as i said before. it needs a mastering pass badly, and some more attention on the arrangement side to prevent feeling like it's two minutes of content scraped over five minutes of bread. another look will really help bring this up to your more recent standards.
NO