I am surprised that no one has mentioned the very basics of FB adverts - what are you advertising for ?
It gives you options to optimize your adverts for Conversions (different thank link clicks) or video views or catalog sales amongst several others. Those trying to 'hack' their way in FB ads, it is common wisdom that you to let them mature and they keep getting better with time.
When you talk about CTR it is a rate - which means how many times people actually click on your ad when they see it - now CTR would vary according to the 'Purpose' you assign to facebook. I think its important to drive right traffic to your site (and pixel) so that you allow the algorithm to mature, and mature with relevant data - data of people who intend to do, what you want them to do.