On the risk of looking like a lunatic philosopher, yes, I’d argue that gravity doesn’t exist.
Even if energy is not manmade, the concept of energy is, or in other words: we invented this concept in order to more easily understand phenomena around us.
I see a lot of replies saying that “energy is in all things and is immutable”, but we (at least I) can imagine a scenario where someone invents a whole new system to describe nature which might not use the concept of energy at all (or any other concept you choose, such as gravity). The nature can be the same but the way we describe it can vary wildly (more likely beyond human comprehension).
Yup, we are in agreement, though I might have missphrased my comments to imply that one shouldn’t believe in energy
To that end, there is a quote from Dumbledore on one of the Harry Potter films (don’t know which one) where he says: “of course this is in your head Harry, but does it make this less real?”