How to fix this stagnant-ass meta.

Ever since Season 1 worlds, the meta has been the same.

Tank/Bruiser top (or someone to counter tanks/bruisers). Mage/assassin mid Jungler of the week Marksman ADC (Morde and Ziggs on occasion) Babysitter Support (A roamer here or there, but even those hover around bot)

So, 1/1/2 with a jungler is the only acceptable meta.

Compare this to similar games.

In Dota, there's: 2/1/2 3/1/1 1/1/3 1/1/2 jg 2/1/1 jg 1/2/1 jg 2/2/1 1/2/2 2/1/1 roam 1/1/2 roam 1/1/1 roam and jg 1/2/1 roam & the Meepo Special.

(note: 2 mid only happens when Io is in the game)

In Overwatch there have been (that I know of): (tanks/healer/dps) 2/2/2 3/2/1 3/3/0

In HOTS, there are assloads of maps, and a unique meta for each.

Obviously, it's not necessary to have a laundry list of lineups, but having the same one in every game since it became seriously competitive is a problem.

Alright, so what causes League to be stagnant?

1. Junglers are mandatory.
2. Marksmen are such strong generalists that there is no reason to pick anyone else to fill the carry role.
3. These Marksmen are heavily reliant on support to survive the early game, so they force one player to drudge along with them.

Alright, so lets address these one by one. (Supports being forced to lane with their marksman is an indirect problem of marksmen, so I will address them simultaneously with ADC's.)

Junglers

Ok, the goal here is to make Jungling a powerful strategy, but not mandatory. You should be able to run something else if the situation calls for it.

What causes junglers to be mandatory?

1. Jungle camps are too easy to clear. It should still made clear that not all of these should be made to be godlike, but making it so there is actually a downside to farming these would make the role less required.
2. The map has too many jungle camps packed into it, for its size. A jungler can't walk through his jungle for 5 seconds without coming across a source of gold.
3. Smite is straight up OP. If you don't have it, you lose the game. Period. Junglers need a tool to get through the early game, but Smite offers too easy a way of securing objectives.

Ok, so what do I reccomend?

1. Restructure the jungle. Put a buff camp in the center of each quadrant, and have 2 camps wandering around that quadrant, which aggro onto the first champion they see (similar to the Blood Moon spirits).
2. Make jungle camps harder, but more rewarding. They should be tanky and threatening. If this makes them too hard to deal with, you can tweak the way jungle camps work for some creative modes of clearing the jungle . For example, making them chase REALLY hard and be vulnerable to towers would let fast champions jungle by aggroing a camp and then using a turret to bring it low. Another possibility is to remove resets/patience, allowing kite junglers to be viable.
3. Rework Smite. Either change its damage to (250-400 +25% targets current HP) or turn it into a spell akin to Spirit Fire, but with a smaller area. This would make it so that not having smite doesn't instantly lose you every objective, so you don't need to have smite. Every objective fight becomes a chaotic scenario where even the Janna can snatch that Baron. Nunu and Cho become competitively viable for their ability to secure epic monsters.
4. Remove "Special Bonus XP".
5. Tweak jungle champions so that none are left in the gutter (I'd imagine Fiddle would like a word with you anyways)

Carries The goal here is to make Marksmen no longer mandatory in the duo lane, to open up the botlane carry role to other classes, and to make carries not so incredibly reliant on their support.

What causes these problems?

1. Multiplicitive Scaling with AD, AS, and Crit combined with the range of an ADC turns most marksmen into a generic blob of stats by the end of a game.
2. Playing anyone other than an ADC (or Ziggs <3) in the carry slot will result in your team being unable to push, ssince you will lack the ability to do significant damage to the tower from long range.
3. Melee carries get kited far too easily.
4. Marksmen are so weak early that almost all of them need a support to stay with them for the first ten minutes in order to

Reccomendations:

1. Turn Max AS into a stat unique to each champion, like their range. Some champions could have a very low max AS (Jhin), and others could have a higher max AS (Kog). After taking this into account, you could tweak base AS/AD values to make champions with lower AS values hit harder. For example, Tryndamere would likely have his AS capped at 1.5, but his base AD increased to compensate (maybe a buff to his E CDR for crits).
2. Change Seigemaster to something resembling the old T2 tower shield. This would make it much more difficult to towerdive carries early on, making it possible to lane alone as a marksman vs a 2v1 lane (making roaming supports viable. Smite Singed/Nunu, Rivershen, full roaming Bard... oh boy!).
3. Increase starting gold to 850. This allows players to have much more versatile starting items to fit their needs, further increasing the ability of marksmen to survive early, but also makes other champions (particularly supports) much more versatile with their item sets. "Am I a 1v2 Vayne? Hmm, maybe a Dblade+Dshield/CorPot to survive the poke" "Am I playing Mundo into a Quinn? Dshield+Corpot it is!". "Tryndamere Blitz bot against Kog+Janna? Lets go Double Dblade to destroy them early!" "Hmm, I can afford T2 gold gen, SightStone, T1 gold gen and boots, or... so many options! How much sustain do I need?"