Much of this sounds like meta-contributions to hard science -- methods of comprehension and abstraction, not insignificant, tho -- rather than contributions to the corpus of that science.
If true, what's wrong with that?
Russell's theory of descriptions cuts no ice with linguists. It is a (failed) attempt to explain how proper names work. Fodor's absurd "language of thought" junk is ignored by neuroscientists, and Dennett's "Consciousness Explained" is aimed at debunking mentalistic myths that have plagued philosophy since the time of Descartes. He uses the findings of modern cognitive science; he is not a contributor to them in any sense.
Philosophy has become irrelevant to science, and no philosopher from the nineteenth century on has made any contribution to science whatsoever.
I'm rather sure that Russell's Theory of Descriptions is a semantic theory of, predictably enough, descriptions, though it is true that he applied it to proper names as well. Independent of the truth of the Theory -- and probably descriptions
don't literally have quantificational structure -- it has spurred a century of productive debate and any linguist will recognize it as a contribution to their field (just ask).
I mentioned Fodor's modularity thesis and not his Language of Thought Hypothesis, though both are major contributions to the 'mind as computer' paradigm that is so widespread in cognitive science. Again, this is the case whether the hypotheses are true or not and can be confirmed by experts in the field. Your denial of this seems to hinge on the implicit claim that neuroscience is the only 'real' science of mind, a contentious claim.
Finally, while Dennett didn't "contribute" to the study of consciousness in any direct sense, he did synthesize cognitive science research in an interesting and productive manner. You might have an overly narrow definition of 'contribution' if only the production of experimental data counts as such, something it looks like you might be implicitly claiming.
Philosophy won't necessarily continue to contribute as it has in the above examples, but
that it has as a contingent matter of fact seems to me undeniable.