Okay, final try.
Look at the way Mana works and think about real human energy / stamina.
Champions use Mana to do things, you use to much you will run out and be no longer able to use anything. A human being can get into a soccer/basketball/<insert sport> and run/jump/kick/etc. If a human being exerts themselves too much, they wil become fatigued and regardless of their fitness level, become less effective (muscle pain, cramps, hunger, etc). This is exactly the same as how Mana works in League. When a marathon runner paces themselves so that they don't tire out too quickly, it is the same as Mana management. Why do they do this? So that they still have some reserves for the burst at the finish, just like how Mana users in League can manage Mana in lane and wait for the right opportunity to unleash a barrage of abilities. If you use up all your Mana at once, you are forced to wait for it to be replenished; potions take the place of food/drink while returning to the fountain essentially takes the place of rest/sleep. Once again, how do you not see this? Why are you even refuting it?
The alternative resources to Mana are so unnatural in the real world. Who in the world has never ending Stamina like Garen while simultaneously being restricted to a finite number of actions due to time? There are no humans that have energy which regenerates like the Ninjas or Lee Sin. If we had a robot that had its own renewable energy source (e.g. solar power), that would be the closest we could get to a direct comparison because said robot could theoretically expend vasts amounts of its energy and regain it relatively quickly; this is of course as compared to human fatigue and recovery.
Your argument is flawed because you want this make sense when in fact Mana is the closest comparison to making sense. I'm not even attempting to be really hostile towards you, you simply refuse to face facts; it doesn't matter what does and doesn't make sense OR if dunks are magical. You are entitled to your opinion but when you blatantly ignore a bunch of people that explain and the others who didn't even see value to post because they flat out disagree, you need to at least reexamine your stance.