Credits:
All sound effects included as a file in the character are either by Scott Lowe & Philipp Lenssen, Freesound.org under Creative Commons ( https://creativecommons.org/licenses/by/3.0/ ), or either of them but couldn't find the proper credit link for. Thanks to any according sound creators.
Here are ones I've dug up:
"Boost" and "Boost End" sounds are edited from a sound by Chipfork. https://freesound.org/people/chipfork71/sounds/72639/

Victory theme is trimmed from "Where's My Banjo" by Rimsky (Salvador Fornieles & Carla Olaortua)
All of the characters' designs including the alternative costumes and the "Philipp" costume were created and designed by Scott Lowe & Philipp Lenssen.
All of the various Manyland base-game elements (E.G. UI, particles, etc) were designed by Scott Lowe & Philipp Lenssen, and excluding the text, were referenced and re-drawn by Hyuponia Halfmirage.

All of the various items that is not the Manyland base-game elements (E.G. Solids, Deadlies, Equipments, etc) were all created by someone in Manyland, and were referenced and re-drawn by Hyuponia Halfmirage. Thanks to any according creators, which I will list them below with the names at the time of writing:

Solid (Used for NSPECIAL, FAIR, FSTRONG, and DAIR)
Solid 1 (GRASS TOP) created by Philipp.
Solid 2 (MANOR PATIO) created by Nicole.
Solid 3 (SLATS) created by Stitch.
Solid 4 (STARBUCKS TRIBAL) created by Cerella.
Solid 5 (RAINBOWPIPE) created by Kobo.
Solid 6 (DECORATED HORIZONTAL) created by Fredley.
Solid 7 (TILE FLOOR) created by Morsmage.
Solid 8 (BRICK WALL) created by Morsmage.
Solid 9 (Concentrated Minfinity) was not referenced by a Solid in the game, but were created by me, referencing the minfinity background.
Solid 10 (Ground) created by Philipp.

Bouncy (Used for USPECIAL)
Bouncy 1 (TRAMPOLINE) created by Philipp.
Bouncy 2 (SHROOM) created by Myookat.
Bouncy 3 (SPRING) created by Stitch.
Bouncy 4 (BLUE SHROOM BIG) created by Becca.
Bouncy 5 (GUMDROP) created by Witchhazel.
Bouncy 6 (STRAWBERRY BOUNCE) created by Quirky.
Bouncy 7 (SPROING) created by Goblette.
Bouncy 8 (TALL FANTASME CAVE SHROOM) created by Ibby Wondrous.

Harmful (Used for UAIR)
Harmful 1 (FIRE) created by Brando.
Harmful 2 (BARBED WIRE) created by Leox.
Harmful 3 (SPIKE) created by Chad.

Deadly (Used for DSTRONG)
Deadly 1 (LASER) created by Budgie.
Deadly 2 (SPIKES) created by Lordy.
Deadly 3 (MUSTER) created by Dude.
Deadly 4 (STAR BLADE) created by Philipp.
Deadly 5 (SHARP CRYSTAL) created by Philipp.
Deadly 6 (SKULL) created by Pickachu.

Equipment (Used for JAB/FTILT)
Equipment 1 (WIDE RANGE SWORD) created by Philipp.
Equipment 2 (STRONG SWORD) created by Philipp.
Equipment 3 (BAN HAMMER) created by Grim the Reaper.
Equipment 4 (HEAVENLY SWORD) created by Celladoro.
Equipment 5 (LEGION SWORD) created by Dirge.
Equipment 6 (DOUGHNUT WAND) created by Okra.
Equipment 7 (CROWBAR) created by Philipp.

Item (Used for DTILT and DATTACK)
Item 1 (GOLD COIN) created by Philipp.
Item 2 (PINK GEM) created by Philipp.
Item 3 (MANYMUG) created by Philipp. (A real merch!)
Item 4 (BASKETBALL) created by Budgie.
Item 5 (Flag) was not referenced by an Item in the game, but were created by Philipp, referencing the report flag.
Item 6 (ON BOARD) created by Qusion. (Rest in peace...)
Item 7 (HOTDOG WITH MUSTARD) created by Ari.
Item 8 (FIRE STAFF 2) created by Scarlettmoon.
Item 9 (STANDARD STARBUCKS CUP) created by Cerella.
Item 10 (MONEY) created by Nicole.
Item 11 (TROPHY) created by Cadbury.
Item 12 (KEY E1A5D626) created by Baal.
Item 13 (BOWLING BALL) created by Ari.
Item 14 (BEACHBALL) created by Exetaldotexe.

Item Thrower
Item Thrower 1 (CANNON) created by Leox.
Item Thrower 2 (ITEM THROWER) created by Myself.
Item Thrower 3 (CANNON) created by M0o3.
Item Thrower 4 (IMA LUANCHING MY LASER)[sic] created by Moewzerz.

Emitter (Used for USTRONG)
Emitter 1 (SUN BOW) created by The Knight.
Emitter 2 (TRI BOW) created by Da Beast.
Emitter 3 (LONGBEAM RIFLE) created by 3dollarbill.
Emitter 4 (ROCKET LAUNCHER) created by 3dollarbill.
Emitter 5 (GUN) created by Adeleine.
Emitter 6 (FUTURE-ELECTRIC-MAKER) created by Kid.

Epic Gun Dynamic (Used for BAIR)
Epic Gun Dynamic 1 (EPIC GUN) created by CHILL BILL.
Epic Gun Dynamic 2 (DA BO$$ GUN) created by Stalker.

Wing Dynamic (Used for NAIR)
Wing Dynamic 1 (FALLEN ANGEL WINGS) created by Archer.
I became too lazy to make more wing variants so there's only 1 right now

Chair Thing (Used for TAUNT)
Chair Thing 1 (ICECREAM CHAIR) created by Quirky.
Chair Thing 2 (COMFY CHAIR) created by Entariel.
Chair Thing 3 (CHAIR) created by Zorrie.
Chair Thing 4 (BEANBAG CHAIR) created by Dinnerbag.
Chair Thing 5 (CHAIR??) created by Okra.
Chair Thing 6 (STONE BENCH) created by Morsmage.
Chair Thing 7 (WOODEN DARK IRONED BENCH) created by Victor.
Chair Thing 8 (CLOUD CAFE CHAIR) created by King.

Double Jump Wearable (Used for doublejump)
Double Jump Wearable 1 (FIRMAMENT WANDERERS BROOCH) created by Cyel.
Double Jump Wearable 2 (SKYHIGH RIBBON) created by Hyuponia.
Double Jump Wearable 3 (KITE) created by Justas.
Double Jump Wearable 4 (LACE PARASOL) created by Quirky.
Double Jump Wearable 5 (ANTLERS) created by Deer Lord.
Double Jump Wearable 6 (TOP HAT) created by Payton.
Double Jump Wearable 7 (SUPER PARASOL) created by Ari.
Double Jump Wearable 8 (PIPE) created by Sir Azuresh.
Double Jump Wearable 9 (PARTY HAT) created by Justas.

Double Jump Wearable 1 (LONELINESS RIBBON) created by Hyuponia
Double Jump Wearable 2 (ORANGE FISH YES) created by Lileepia.
Double Jump Wearable 3 (CROWN) created by Aaron.
Double Jump Wearable 4 (ROMANIAN HELMET) created by Zo.
Double Jump Wearable 5 (ARMOR OF THE LOST HERO) created by C.K.B. (Captain King Brown)

Double Jump Wearable 1 (SHIELD ALL SEE ALL) created by Philipp.
Double Jump Wearable 2 (ANGEL) created by Polis.
Double Jump Wearable 3 (DEAL WITH IT SUNGLASSES) created by Assassin112.
Double Jump Wearable 4 (GAS MASK) created by !Jonny!.
Double Jump Wearable 5 (STAR) created by Raccoon.
Double Jump Wearable 6 (FORCEFIELD) created by Big Dummy.
Double Jump Wearable 7 (BOW HAT) created by Okra.
Double Jump Wearable 8 (DOC MASK) created by Fifteenoj.
Double Jump Wearable 9 (A SOMBRERO) created by Mabel Pines.

Respawn Platform includes:
GREEN MOUNTAIN GRASS LEDGE by King.
TILED GREEN MOUNTAIN by King.
GRASS LADDER BACKLESS by Hadron.
VINES by Fredley.
RING PORTAL A by Philipp.

Victory screen background includes a lot more creations, but they were based off of screenshots and cannot quite pinpoint credit names. I apologize for not being able to credit everyone proper.

The splash art "subtitle" ("Denizen of Many lands") idea by Cyel!

Manyland is copyright by Scott Lowe & Philipp Lenssen.
Manyland(TM) is a trademark and service mark of Scott Lowe & Philipp Lenssen.
Thanks to the makers of devices we build on.
Thanks to civilization whose shoulders we stand on, coffee, tea, and the universe in general.