At the most basic level, the cardinal rule if you want to work and succeed at a company is to make your boss' job easier. When asked, "what can you help with?"

At the most basic level, the cardinal rule if you want to work and succeed at a company is to make your boss' job easier. When asked, "what can you help with?", you said "you'll do anything they need" and thus transferred the work to them to figure something out. That's not good. They already have enough to do. So if you had said, "I have thought a lot about this, and Ii think I can do x, y and z to start and potentially a, b and c later", my gut tells me the outcome would be different. Offering to do a free internship is indicative of moxy, but offering to do a free internship and having a plan on how you can contribute is truly valuable. Best of luck.