I played for about an hour all without items (see picture of the furthest I got), then read some of the comments that said I could trade the statues for items. I chose the shoes and, honestly, I played for about 10 more minutes and didn't notice any changes.
I'm guessing you're looking to Jump King as a form of inspiration, which I never played, but does explain why this game is seems hard and punishing--so if you that's what you're going for nailed it.
The movement feels sluggish which I think clashes with the character design (when I see a kangaroo I imagine I shouldn't be this slow). It'd be nice to be able to turn faster along with the slower speed and it would also be nice if you could buffer the jump input while airborne, which would've definitely helped out whenever I adjusted my position with a series of small-hops. UPDATE: I've played a little bit more and realized that the shoes let you double jump--I guess make the jump-buffering only happen without the shoes, but now I want faster turn speed more even more.
Both the character design & animations are very charismatic and you did nail the PSX/N64 aesthetic 100%--great job there!