I'll happily give some more in-depth feedback seeing as my review of your hack was short and sweet as well as been to the point.
Looking back and playing through the first three levels in World 1 I saw the immediate pattern take effect.
Pretty standard and safe for a first level which is too be expected. Nothing really wrong with it other than it been generic.
It doesn't help that it's Grassland themed as that will be another issue we get onto later on.
Honestly this level is only bad as the Tutorial Level prior introduces a small walljump required section which is longer than anything you can walljump on in the first main level.
I'll dive on this topic later as well.
You introduce a new enemy (Sleeping Goomba) in a rather impractical way. You go past the first screen and bam it starts chasing you.
Having it in an area you can't access or having more time to react to it would of been a better introduction.
Once introduced correctly you can then use it in surprising ways to keep the players on their toes as they'll already feel comfortable getting around said enemy.
Once again there are no real emphasis on the walljump and we are in the second level. Another point for a more in depth section.
Mushroom Platforms had some interesting layouts however the Hidden Passages do seem sorta random granted nothing too bad.
In the Switch Palace Area you do have a Sleeping Goomba hidden behind one in which the player can easily hit due to having no prior warning to it been there.
That's all for the levels I decided to thoroughly look into again as these three alone paint a pretty good picture for the hack.
Before I continue I just want to say don't think I am talking with an ego or some idea that I am the best SMW hacker ever.
I look back at my old work constantly and it could of been waaaaaay better. My Super "Mario" World 2 hack really goes insane with bullshit hard level design in the latter levels which just is not fun.
Over the past 10 years I have been trying to "perfect" my level design philosophies and how I tackle building structured levels.
I want to pass on some advice from what I have learnt so you can maybe go away and see what you can improve seeing as you are asking for advice.
Anyways lets move onto some of the biggest points I'd like to discuss about your level design and hack in general.
Generic Isn't Bad It's Just Not Interesting
Something I find to be odd is you have really distinct levels later in the hack yet for many of your world and level themes you keep the visuals and overall style very safe.
Your first three levels all blend together bar different palettes. It also does not help that you used a Grassland for the first theme.
It's not bad as everyone has done it. It's just I feel we need to stray away from the Standard Mario Formula and be more creative.
Why can't World 1 be a hot Savannah themed world with dry plains and small overgrown areas.
Heck throw in some lava as well why just save that for castles and later worlds? (looking at you every World 8 in 90% of hacks...)
If you have not seen of played Donkey Kong Tropical Freeze I urge you go look at game for level aesthetics. Each level in World 1 has its own thing to set it a part and that theme follows throughout the entire game.
Don't limit yourself to the common norms we see in most Mario games. Break the mould and think outside of the box.
Having a really interesting set of levels early one with a distinct theme will keep players interested in continuing to play your hack as well as making it stand out and be generic.
Plenty Of Gimmicks But No Twists
You do introduce new enemies and gimmicks regularly which is great however you don't add twists or new spins to them. They show up and then they'll show up again later on.
For Twists introduce a concept in a way the player will grasp quickly. Build upon and test their skills with it be it a challenging enemy or platforming section that focuses around that gimmick.
Then introduce the twist. It'll be the same idea but you have added in a new element.
This can be a new enemy or block or anything that changes the way you go around using the existing gimmick making the player think hard and thus leading to more rewarding experience.
I recommend looking at Mark Brown's video on Youtube about Super Mario 3D World and it's level design structure. It's essentially what I've just said plus it's a great watch as well.
Less Is More: "Quality Over Quantity"
Honestly a lot of this hack could of been condensed down into fewer levels and fewer worlds focusing more on stronger designed levels and more planned out gimmicks for each level to really bring about a greater sense of identity.
If you levels all blend together it's hard to pick one out or remember anything that was truly worth going "oh yeah I remember that level it was really cool".
If you have time to make all these cool Vanilla SMW styled GFX for levels then you can try harder and make each level stand out more. Not every level in a grassland should look identical.
I know you can do more but I do know how easy it is to just re-use assets to save time.
Some of your levels really do pop so I'd say it's like a Double Edged weakness for you. Nice Visuals but Weak Design. Get the balance down but focus on design first. It can look like shit but if its fun to play its fun to play.
Like most hacks Mario feels like SMW Mario. Adding in a walljump means you don't have to abide by the same rules and layout as standard Mario levels. In the New Series walljumping is a thing but its not heavily utilised.
Like in this hack there are only a few levels that heavily use it and it's usage is sparse in between those said levels.
Why have it if you won't use it? Why make levels that are simple go left to right? With LM3.0 get Vertical with your levels if you have the walljump as the level layouts expand tenfold.
Closing Points & Conclusion
If you have the time to go all out on a hack this size you are more than capable of spending time to focus on building on your hacking skills.
I'll say though all the criticism I have seen is fair. It must be striking a cord with you if it's enough to make you post this thread... and guess what that's a good thing. You are wanting to improve and well done.
You could easily made the third hack in this series and called it a day by mimicking the past two and playing it safe.
From this point going forward I'd say work on a small hack of a few levels working on your designing skills. Let people play it and get more feedback. Once you have it pretty much down you can then start building back up to a hack of this size again.
Granted you can do what you want at the end of the day but like you have said yourself if you don't wanna be known as someone who makes generic styled hacks you'll have to jump out your comfort zone and take some risks.
I'll always remember a distinct hack even if the levels are odd over something that looks like the same type of stuff that is constantly been pumped out. Once again this is to not insult or discourage people from making more generic styled hacks.
It's just if you want to stand out you gotta make your work actually STAND OUT.
I believe you can do it and I hope you read all of this.
If it's too long then please read at your own time and pace but when I see your next project I'll be looking to see what you are doing differently.
So yeah Good Luck. I know you can do it.
Feel free to PM me or hit me up on the Discord to talk more if needed.