PMs are not elected, only MPs who later exchange letters. It's the same as the Speaker of the House in the US.

The Morel quote is from a political opponent: such words are quite common in such situations.

You neglect to mention that after being voted out, Churchill was voted back in after a period of "is the grass greener on the other side of the fence?"

I have read concerns others wrote in the pre-WW1 period about an up-and-coming Churchill, one being "He will write his name big on our future. Let us take care he does not write it in blood.". He had too little fear of military action - in spite of seeing combat - and deeply believed in the virtues of Empire. Something like Teddy Roosevelt in a way.

It's possible that in an alternate universe Churchill might have been responsible for millions of deaths in the name of Empire. In this universe, however, he chose the opposite path from Hitler.

This is reasonably balanced article on the issue of Churchill's strength's and weakness.