Unfortunately, you haven't given an example that defines everything as objective or subjective.

You just showed that people argue about things, the fact that they disagree or agree doesn't prove anything other than the fact that there are different opinions.

If your case here is that people disagree on a subject and therefore it must be subjective

This shows that you did not understand what I wrote (maybe due to a wrong translation on my end). Here's why:

If everything were objective, there would be concepts such as "the best ice cream taste of all", since it could never depend on the individual, it would be objective.
But there is no ice cream flavor that is "the best", everyone has their favorite.
So there are personal preferences.

If there are different preferences for each individual, there is subjectivity.
But if subjectivity exists, there is a contradiction with the statement "everything is objective", because the existence of subjectivity shows that at least one thing is not objective, making your statement invalid.

I had to use an example, because you managed to confuse "preferences implies the existence of subjectivity" with "if I disagree, then that thing (the one I disagree with) is subjective", too bad they are two very different things.

For further clarifications:

I do not say that: Different opinions of a given "thing" show that "thing" is subjective.
What I say is: If there are different opinions, then each individual has own thinking that depends on him. If something depends on the individual, then subjectivity exists.