Metagaming

First, lets kill the metagaming ad hominem: "Metagaming is any strategy, action or method used in a game which transcends a prescribed ruleset, uses external factors to affect the game, or goes beyond the supposed limits or environment set by the game. Another definition refers to the game universe outside of the game itself."

Optimising a combat-oriented character to be good at combat within the rules is not and never can be metagaming. You can't even mount a game universe argument that it is: a person who has devoted his life to being a wilderness warrior (aka a Ranger) is going to learn to be good at fighting or die!

Comparison

Hit Points

Your hit point edge is insignificant; an 11 hp advantage is, on average, 2 hits or 1-2 rounds more staying power in a combat (less if fighting multiple foes). When you consider that the Paladin has an ability to heal 15 hp with their Lay on Hands ability at the cost of an action, they effectively have more hp than you do. You do have a definite advantage if you are being hit by things like fireballs; on failed saves you are the only one left standing.

This is an edge but a small one.

Damage output

I will assume everyone has the same stat modifier on damage rolls.

If you are using your bow and choose to use a spell slot for Hunters Mark, you can do 3 + d8 (bow) + d6 (Hunters Mark) (avg 11) on the first hit and the same plus d8 (Colossus Slayer) (avg 15.5) on subsequent attacks. This is great if you are fighting a monster with lots of hit points; it is not so good against a dozen goblins since the first hit will drop them and your Colossus Slayer never kicks in.

Meanwhile the Paladin with a longsword and the dueling fighting style is doing 3 + 2 + d8 (longsword) + 2d8 (Divine Smite) (avg 18.5) (I haven't considered some of the really cool spells they have).

The Rogue is doing 3 + d8 (longbow) + 2d6 (sneak attack - a good rogue should almost always get this) (avg 14.5).

The Sorcerer has a plethora of options (Magic Missile, Burning Hands, and Cloud of Daggers spring to mind) or they can just fall back on a damaging cantrip for d10 (avg 5.5). If they are a gambler, Hold Person can end a combat with a single humanoid on one failed saving throw.

If the Bard wants to be handing out massive damage in combat then they chose the wrong class; that is not where their talents lie, they are an enabler - they enable others to do more damage.

The Ranger is not the best at handing out damage.

Overall, you are playing your character to his strengths; are the other players playing to theirs?

Pacing and Encounter structure

You say "I was typically able to go first in any combat due to high DEX, and dealt such insane damage that the guys going last did nothing".
I read "The encounters are underpowered".

Don't misunderstand me: it is the nature of RPG that the PCs will win (almost) every fight because they can only lose once. Most combats will be and should be cakewalks, they are there because combat is fun and they consume resources. That said, they shouldn't be so insignificant that they are over before the first round ends. A quick combat like this is great if the players have planned and executed a great ambush, its not great if it is just way underpowered.

If you have enough spells to use a spell in every combat then you are not having enough encounters between long rests. Burning through spell slots for a non-core spellcaster should be a tough decision: "Do I use it now or will I need it latter?" If you are not thinking this, at least briefly, all the time then your DM is being easy on you. Fights early in the day will usually be easy but this is due to everyone having lots of resources, as you burn through spell slots and hp the same encounter becomes much harder.

Also, the structure of encounters matters. 5 PCs on one monster is an easy fight (unless the monster's CR is extremely high for the party); the monster can only target 1 PC while copping damage from all 5. 5 PCs on 5 monsters is much harder; the tough PCs have to control the battlefield or the squishy PCs will get squished. 5 PCs on 15 monsters, even very weak monsters, is really hard; everyone is copping damage and the fight will last 4-5 rounds minimum.

Your problem here isn't primarily the selfish individual, but the GM who is letting his out-of-game best friend run roughshod over the game. You need to talk to the GM, first, about how the game is starting to not be fun, then (likely) talk to the GM and the problem player about why.

Be prepared, though; this is probably a lead-up to quitting the group and finding another group to play with. You should assess whether it's worth the conflict to try to stay with this group, or if it's easier to just find another group.