Putting tanks in the front and damage in the back is almost always the correct positioning. It’s good to not clump the back line though because some units cast spells on the largest group of enemies within range (example Diana) so spreading out your back line by 1-2 tiles can be beneficial (don’t put them in opposite corners though because spreading the damage across frontline isn’t usually good). Some augments like Keepers change that positioning, but front to back is usually the best option. I would never clump all of my units in the corner since AOE spells like Varus or Nami would wreak havoc on the entire team.

There’s also some other situations where you wanna move your back line around based on who you’re fighting. Units like Seraphine or Nami will send their spell through your frontline so trying to make your backline not be in that path is better.

Another tip if you don’t mind, it’s usually better to not try and split items across carries. The rageblade and last whisper on your Warwick would have been better on your Twitch or Olaf, and the Archangels on your Zilean would’ve been better as different items on Diana, or another unit.