Without looking through the internet for help it is a steep learning curve for some new users. A massive part of Apple's product is having the support to complement it, in this case the Genius Bar, and also telephone support.
I first got a macbook around 6 years ago, and I also struggled to work out how to rename a folder. I achieved this learning by playing around and eventually found out that I could do this by 'Get info' and rename there (did not realise enter achieved this until today!).
The main issue with making more options obvious to the user could actually backfire. I am using Yosemite, and we have 8 items (other than back/search) on the top bar. We have a hover over which tells us what each of these things do which is of help. Adding anything more to this bar and you have a very complex interface - see Miller(1956) Short term memory can only hold 7 items +/- 2 items.
Comparing this to Windows we have a similar approach which I think is better. Windows use a right-click -> rename which is far more intuitive. If you need information about the file you right-click -> properties.
It is a hard to design a system which is 100% obvious to use, it is much like photoshop to some extent, looking at the interface from a strict UX perspective, you could say it was overcrowded and confusing and a first time user would be flummoxed.
From experience I look at photoshop and think "Where do I even start?". But this is okay in this case, people who use photoshop are using it mainly as power users - they understand there is a learning curve, but once they have learned it their workflow would be easier.
This does apply in this case, to make every feature of an operating system obvious would be a mess - you cannot get rid of the feature so you hide it instead. If you are a new user and going to use your mac regularly, then you would invest the time to learn.
To conclude, Mac's are a learning curve for any level of user but Apple provide appropriate support to get anyone started. They have an actively maintained support forum and there are many resources on the Internet. But OS X just like any operating system is not 100% obvious as they are too complex.
Some useful resources:
Millers Magical Number 7
UX Stackexchange Question - Top answer has some useful points
Minimising Complexity in User Interfaces