No evidence exists for gravity as we know it, to have existed, why would I need to disprove it???
Because if gravity didn't exist in the same manner that exists now (or at all, as you seem to imply), you suddenly have more problems to explain:
1) How did solid objects remain on the ground, without flying off into space.
2) How did the Earth remain in orbit around the sun for however long it took for modern gravity to come into being?
3) Where did modern gravity come from?
There are more, but those are some great places to start. Find some reasonable explanations for these, and I'll start to think about accepting your argument.