It's a coherent theory with evidence though. Gravity is just a theory too. Before scientists discovered theories of gravity, gravity already existed. But you can have different theories of gravity, Einstein or Newton. You can have different theories about evolution too, but scientific theories are not just blind speculation. The word theory doesn't mean it's unproven. Some theories can be proven, like Einstein's theory of relativity is proven to be correct.
I'd be very interested to learn about such evidence! Has there ever been an evidence on the proposition that we, humans, evolved from apes?
In fact, there are many evidences that prove the opposite including simple observations that require basic logic.
Yes, you're right; "the word theory doesn't mean unproven", but it doesn't mean "proven" either. It remains a "theory" until it gets proven.
And so raising it to the level of "fact" is unscientific and biased to say the least.