Things I know from having friends that only play aram:
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ARAM is not balanced and is not supposed to be balanced. Riot very rarely makes ARAM specific changes (although there are some coming soon). As Pika Fox said, its intended as a dice roll.
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ARAM has far fewer players than SR, so the matchmaking has to stretch farther to find 10 players to put in a game. That's why you end up with a larger rank disparity than SR.
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Ppl dodge when they don't like their champ/team. The diceroll nature and the fact its not the primary mode means ppl don't care as much about dodging.
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ARAM is, more often than not, a bloodbath. This puts the game on a knifes edge; either one team snowballs or both teams keep dying leaving you with a volatile standstill. The tactics used in SR to stall and spread out don't exist here, ARAM is feast or famine.
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Most ppl only care about fighting in ARAM, so CS loses meaning and most people I see do a terrible job last hitting. if your kill gold is on the wrong person, you're fucked.
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By "damage champion" I assume you mean Marksmen, assassins, or fighters. Many of them have weak early games compared to tanks and supports who are expected to get less gold and so are given stronger base numbers. Most assassins are expected to get a fast 1v1 kill, not extended 5v5s fights. Fighters typically do well either over a long slow fight (stacking buffs w/o getting nuked) or numerous shorter fights (short combo > disengage > repeat). Fights can be long, but if they have a mage you'll get bursted, and the only continuous short trades are going to be poke champs. Unless you cleanup kills and get items they are supposed to out-trade you.
Given you cannot commit time for a longer game then you honestly are better off playing something else. League is built around SR which averages between 20-40 minutes. OW is much faster, Fortnite probably not going far over 20m if you survive. If it honestly is just the RNG that you hate, play twisted treeline. Its faster than SR and doesn't deal with the dice roll bs.