Science claims that ID is not testable. Neither is any alternative claim. One cannot experiment on the past. One can only observe and interpret.
Take Max Plank's quote “Experiment is the only means of knowledge at our disposal. Everything else is poetry, imagination.”
If we stick to that as the absolute rule for science and knowledge, and avoid arguing by human 'logic', what do we really and truly know? Not much.
Unusually, you're sort of right here.
And I must admit I do get irritated by some programmes they show over here, there was one "Walking With Dinosaurs" which claimed far more detailed knowledge about their day to day lives and behaviours than can possibly be known for sure.
Darwin's observation which kicked all this off was the way finches on different islands had adapted to their differing environments.
It's a bit of a stretch from there to the whole theory of evolution but one issue here is time. We live and think in human timescales.
Imagining a thousand years is a stretch for us, let alone a million or even a billion years. But even over relatively short timescales we can watch evolution happening
You could say "well, that's just adapting", but if that can happen over 11 days then what could happen over a couple of billion years?
Obviously all we can sensibly do with something like evolution is look for evidence in the form of "if life has evolved then what would we expect to see?". We'd expect to see a fossil record which is consistent with evolution, which we do.
We'd expect to see species which we believe to have had a more recent common ancestor to be more genetically similar, which we do.
We'd expect to see hints of evolution in the anatomy of animals, which we do. We have a coccyx which hints at a tail from our past and we have an appendix which people seem to be able to survive perfectly well without.
Can we know for sure that evolution occurred over huge timescales? I guess not. But it's the best model we have which explains what we observe in the fossil record and makes sense of the genetics in different species. A decent article here on the evidence
https://www.khanacademy.org/science/biology/her/evolution-and-natural-selection/a/lines-of-evidence-for-evolutionThis is like trying to solve a murder where there were no witnesses. There's a good reason the law only demands a case is proven "beyond reasonable doubt", you can always cast doubt on things. One day a better theory may come along which fits the evidence better but right now it's the best we have and the evidence for it is pretty strong. The counter-arguments always seem to be people not understanding evolution or "but my book says..."