I greatly understand your frustration in this. First of all, do you have the elementary theme turned on for your course? This will be a streamlined Canvas experience, making it easier for your students to navigate. If not, you need to contact your Canvas admin about that. This will be in your course settings, in the Feature Options area.
How do I enable an elementary-level theme in a course as an instructor?
Please be advised that this setting does not have the Discussions feature (as well as some other features, such as Assignments) visible to students. If you want to have the Discussions feature visible to your students, you need to make sure to edit the settings for your course navigation links.
How do I manage Course Navigation links?
As far as the Discussion feature is concerned, here's an idea, from a former kindergarten teacher. 
You want to make sure that the students' work is documented so you can easily show it to parents. Discussions can definitely be a great feature to use, if you use it appropriately. Most likely you would not want or expect your students to type in the RCE (Rich Content Editor) in order to post their discussions. How about enabling them to attach/upload a file, such as a picture, a voice recording, and/or videoing themselves? Also, something to consider is the type of devices that they will be using to do so. Will they be using laptops of mobile devices, such as iPads? I would imagine that it would be easier to teach them how to complete this using an iPad as opposed to a computer.
I would also recommend using the Assignments feature, if they are doing homework/classwork. If they are going to submit their work using pencil and paper and not through Canvas, make sure to change the type of submission to "no submission."
Announcements is definitely a tool that you would want to use to communicate with your students' parents.
So there are a lot of possibilities; just make sure you put your education goals for your students first and then see if there is a good way to integrate and leverage Canvas to meet those goals.
Please reply if you have additional questions. You also might want to visit the Canvas Commons to learn how other teachers have used Canvas for younger students. You can find teacher created materials there.
Good luck!
