How are recommended champions determined?
Solution 1:
The recommended champions are the same for every one, regardless of level. They do not change to reflect any of your stats. The champions chosen as 'recommended' are those whose skills are more straight forward than others.
Annie for instance is a burst mage with no utility (besides her passive). Warrwick's auto attacks give him life, as well as one of his spells making him the safest jungler.
In general there is no easy to kill champions in the recommended tab that don't have some sort of escape, excluding maybe Sona or Soraka who are support characters.
Solution 2:
Recommended champions all have low difficulty scores and are considered good starting candidates for new players. Difficulty is an aggregate score that takes into account the technical skills needed by the player to use the champion's abilities efficiently, the survivability of the champion, and its ability to deal damage.