the application of common sense

I don't think you are using the expression "common sense" correctly.

well, in this context, i'm using it to express that i think most people have the same opinion on the matter (may be a misuse, i don't know for sure)

That is not what "common sense" means. Common sense is to do with knowledge, not opinion. It roughly means "good sense and sound judgement in practical matters", or "the basic level of practical knowledge and judgment that we all need to help us live in a reasonable and safe way" or "a basic ability to perceive, understand, and judge things that are shared by ("common to") nearly all people and can reasonably be expected of nearly all people without need for debate.". Examples: It is common sense not to light a fire near where gasoline is stored. It is common sense that you can't get 2 litres in a 1 litre container. Nobody with any common sense would let a child play on a busy road, or expect that coal can nourish a person, or believe that cats can speak.

i fail to see the difference between your explanation and mine other than that i used the words 'have the same opinion' and you used the word 'knowledge', not trying to be rude or anything.

The difference that you fail to see is that opinion and knowledge are not the same thing.

yes, in this context i don't see the difference. whether i replace the word sense with knowledge or opinion in the examples you gave the meaning stays the same from my point of view (although it does need repharsing if changed to the word opinion.)
so i'm not saying you're not right, but i'm still curious about my first question, or does my failure at understanding common sense pretty much kill my point?

Invoking "common sense" shuts down debate. It is a refusal to debate.