As a peel support Janna's main job is to protect her ADC and the team. You can do this job easily because of your kit as it has no real skill shots. Janna doesn't require “much” mechanical skill to perform well with her.

Is Janna a support?

Janna currently has the highest win rate in the entire game—for any champion at any role. ... Her play rate is also the second highest of any other support, currently at 18 percent.

Is Janna a bad support?

The reason Janna is seen as a poor low elo support is because she is more reliant on the ADC than any other champion in the game.