Unfortunately, the game is basically made so that one side loses. Some games will always feel one sided no matter what elo you're in and this is coming from someone who's basically climbed from B3 to D2. My tip for you is like what everyone else said - pick two roles, stick with them. The new champion select basically ensures that you will always get one or the other (assuming your secondary/primary are not fill). Avoid champions that require high skill mechanics until you get more games in (i.e. Vayne, Zed). Thresh, to some extent, is a rather hit or miss champion in low elo due to people not understanding how his kit works (primarily his lantern) or his engage timings, but if you'd like to put some time into him, he's a solid support.
From what I see of your ranked games, a lot of your more "carry" champions suffer greatly due to your CSing ability. I cannot stress enough that CS for a mid/top/adc player is extremely important. It'll improve as you go on, of course, but it's good to start learning some basics now (CSing under turret is easy if the minions are full health: melee minions = 2 turret hits + 1 AA to last hit from you, mage minions = 1 turret hit + 1 AA if you have decent AD).
On adcs, take Warlord's Bloodlust on more utility champions like Ashe or Sivir. The extra healing helps buffer your laning phase and because most of the time you aren't actively poking the enemy laner really. On people like Jinx, you take Fervor of Battle to win skirmishes and to amp your damage up more. For someone like Thresh, go Thunderlord's Decree. It allows you to bully the enemy adc/support easier and procs extremely easily due to how your E passive works. You can go the same for Leona, but you have to be more careful about your engages on her. If you want to go a safer route, as someone pointed out before, Strength of the Ages is a lot better due to the nerfs to Bond of Stone.
Build wise, for your supports, I honestly suggest that you look into what the enemy team is like before building your boots. While mobi boots are good for engaging, etc. there are times where Merc Treads or Ninja Tabi can be better. All AD team = Ninja Tabi (or if 2-3 members are already fed and are primarily AD/AA focused), if the enemy has a lot of CC/AP damage = Merc Treads. The extra utility/defenses that those items give can help you survive a teamfight and potentially allow you to make more plays with either hooks or Leona stuns. I notice that in one game, you built Warmogs on Thresh. First of all, I'd like to point out what Warmog's passive doesn't "kick" in until you have 3k HP. While you did win that game, I recommend building items such as Locket/Randuins before going Warmogs, if you even do go that route. The HP is good, but if you have no resistances, you're generally going to melt anyway. Locket is always a must if the enemy team has a fed AP champion, or even just champions like Katarina or Lux because the extra MR means that it's that much harder for the enemy to burst someone on your team. Armor wise, most of the time I honestly feel that Frozen Heart isn't necessarily worth it's price tag and it's better to go for Randuins due to the fact it gives armor + HP. As someone like Thresh/Leona, you're usually going in to disrupt anyone who is going to auto attack anyway. Spirit Visage is a good third tank item if the enemy has strong AP threats (gives CDR/HP/MR) or Banshee's if they have things that can catch you out of position (Snares/Hooks/Stuns). Dead man's is a good secondary item for armor if you need another one. Build a Mikaels if you feel that your adc may be threatened by something such as Ashe arrow or even a Sona Crescendo. Sometimes even just the extra healing makes it worth it.
Honestly, I can probably give a couple more paragraphs, but some games just don't go your way whether it's how your team comp is built, miscommunication, or some other element that may or may not be in your control. However, if you keep at it, you'll reach the higher elo (hell) sometime! Also, if you plan on playing support, I do recommend adding a few adcs that you enjoy playing with so that you can duo with them (unless you plan on being a pure solo queue player). Having good synergy with your lane partner is extremely important in a game like League.
Sorry for the long post. Good luck on the rift!