The damage in this game is broken

I know I am not the first to say this. I will be saying it again though because it needs to be said. The amount of damage that many of these champions do is absolutely ridiculous. I'm playing top lane against Jayce. We remain even for the laning phase and I have to note the incredibly high amount of damage he does. At level 3 or 4 his long range shot which is ready nearly every 5 seconds does one third of my health from a little over half the screen length away. A little later in the game, still our levels are even, he shoots me with his long range shot and it does over 600 damage. This is close to half of my health. My point is that his regular ability came to the point where it was doing 900 damage when we were leveled equally. How can I compete with someone who is able to chunk half my health from halfway across the screen every 5 seconds? It is broken. It's completely unbalanced and it takes the fun out of the game. His q or w or e or whatever it is does WAY to much damage to be ready every few seconds and cost next to nothing mana wise. In the same game Jhin, who is one level lower than me (playing as teemo) hits me with a trap and his long range straight line shot and it does over 900 damage to me. At the same moment Jayce hits me with his long shot and it kills me. I'm less than one second, with just three abilities, two characters did almost 2000 damage to me. I understand I can buy armor and defensive items. But if I do that, then I can deal next to no damage myself and it will only require them to hit me with one more ability to kill me. At this point in time, TEEMO has been completely shat on. He is extremely slow unless you level all of your points into speed first, in which case, he is an incredibly weak damage dealer. I am stuck between moving at a normal speed and being weak, or being extremely slow and dealing moderate damage. (But no where near enough damage to compete with someone like Jayce). Although Teemo is hated by many players, he is also loved by many as well. I hate that you have completely neglected and made almost unusable my favorite champion in the game. Please fix teemo's weak defenses, extremely, and I mean extremely slow speed, and his absolutely shambolically low range.