This hack has a couple of apparently unbeatable levels and some of them with red dots don't have an apparently secret exit. Also it's not hard, it's even harder. Imo, this would be a Kaizo: Light.
The title screen shows SMB 1-1 level, which doesn't have to do with the hack itself:
Also, overworlds seem to be small edits of the original SMW, here is an example:
Another example, Star World has the same shape as the original SMW.
As for the level design and aesthetics (you've used some custom blocks though), I think you got inspiration from Kaizo Mario World series. Levels itself aren't bad, but not the best either. Screenshots will help you to have a better understanding of this.
In Vanilla Coco Bridge, there is a high amount of munchers (floating and in weird places), which aesthetically are not pleasant to watch, though it is based on Kaizo so I can't say much about it. Also, I can't figure how to get the secret exit, I could't find the keyhole, just the key.
In Baby Sky Tree and the third Sky Tree Jump there are instances of cutoff.
In this section of Sky Tree Roots, sometimes the Chuck will come too late to break the blocks, so it depends on the luck and can be frustrating.
In Linda's Metal Works, there are a couple of instances of design issues:
Old hacks style:
Narrow space with jumping and fire-spitting Piranha Plants and Bullet Bill Generator, making artificial difficulty and probably making the player start that zone again:
Another secret exit I can't figure out is the one in Magma Caverns
(key and keyhole are behind goal post though)
Hydra Path is a non-linear level (there are two ways), the left one with water which
takes you to the secret exit
and the other to the right which is supposed to be fire but it's just red water, you can fix this changing how those tiles act in the tile editor:
Another cutoff in Ted's Cove:
Fun In The Sun is incompleted (at least you activated two-side exit)
and last part of FG with the last sand castle is fake(players can fall through it):
Aqua Tower can't be completed due to the rails acting as a solid FG (this happens in other levels too):
Sunken Ship, although there is a ship, it looks more like an underwater cave.
Mistery Forest 4 is supposed to have a secret exit but I can't find it. Also they are very similar to Mistery Forest 2 and Mistery Forest 3, I guess you thought about original Forest of Illusion.
Forest Oasis should also have a secret exit, I only found short and simple level with the normal exit (green Wiggler) and a kitten in the top of the trunk, maybe that's a clue? Or just decoration?:
Illusionary was a confusing level in terms of design, players could make mistakes between the FG.
Some levels from Star World were good (Dino Hills and Starlite Night, while others could have been better because some ideas were good (Rainbow Run)
One of those levels, Frost Burn, mixes fire with ice. While the idea is good, design isn't outstanding (not bad). This kind of labirynth filled with black blocks made me though they hurt and they didn't, instead they melted with Fire Bro's fireballs:
For the last levels:
Ground Runner has interesting design, but that glitched FG seems weird:
Carrot Fissure was a good level! Intense platforming while avoiding spikes!
Bowser's Castle can't be completed due to the fact that the big red door can't be entered for some reason (tile acting probably), it's a pity because it's similar to last level from Kaizo 1.
In other words, the hack has some good levels and ideas, but some levels haven't the best design. The hack is OK. As a suggestion, you can play other kaizo hacks hosted here to get an idea. Hope this doesn't discourage you, hope this long post helps. Good luck hacking!