[Dimensio]

you dont prove things with science?

That is correct. Explanations in science can never be absolutely proven.

since when?

Since always.

what are observation, testability and repeatability used for in the scientific method? window dressing???

They are used to establish confidence in or disprove a given claim. They will never amount to "proof" of a claim, however, no matter how much evidence acumulates to establish confidence in that claim. There is always the possibility that a given claim will be falsified through the observation of contradictory evidence.

God designed the creatures on this earth.

Please provide evidence to support this claim.