I was lucky enough to have taken shop class when I got into Junior HIgh and High School. I learned to have a healthy respect for the power tools I use. But I don't fear them. Knowledge is power.
I think the best way to learn how to properly use a power tool is under supervision by someone you trust to keep you safe. If you have to use a new power tool and learn it on your own, I check out YouTube videos on how to safely use that tool.
I have been using chainsaws for almost 50 years. I currently have 4 chainsaws of different lengths and strengths. I don't have much fear in felling a tree, but there are times when I have walked away from a situation where I did not feel safe. Old rotted trees can fall in any direction, and a tree hung up on an angle into other trees are called "Widow Makers" for a reason.
I guess, in those rare occasions, I thank God that he gave me the common sense to walk away from a bad or unsafe situation and the courage enough to admit when something is beyond my skill level. It's not fear that motivates me, it's the knowledge that my skills are not up to the task at hand.
As for you using the circular saw, there are a number of YouTube videos that could show you how to use the saw correctly and that should build up your confidence and overcome your fear.
Also, as you get more comfortable with each tool, you get more comfortable with all tools - at least in my experience.