"It's gravity it's gravity, it's gravity, we can measure it, we know planets work by it, we see mass attracting mass." we hear them shout. "So what is it?" I shout.
"We don't know what it is - it just is and that's all you need to know." Is their answer.
Well let me tell you something. If you people rely on something that cannot be explained, then who are the real losers. A clue, it's not those that question this shit.
Do you know something that's learnt by children? It's that asking 'why' enough times eventually ends up with 'it just is' as an answer. It has to, that's just how explanations work. Eventually you get to questioning something so fundamental that you can only respond with "That's just how things are!"
Try it. Why does denpressure exist? Compression of air molecules? Why do air molecules exist? Why did that happen? Why did...
Further, every detail of something does not need to be known, for it to be known that something exists. Case in point: magnetism. Are you going to deny that exists, and suppose some denattraction that draws certain substances towards each other, or do you accept that the evidence is undeniable?
We know gravity exists. Cavendish, for example, is evidence. Your alternative proposal has, not only no evidence in support of it, but is riddled with inconsistencies that you persistently refuse to explain: when they're brought up, you end the conversation. And your only argument against gravity is "But no pull!"
At best that's a semantic argument. At worst, a dramatic oversimplification: as you yourself have stated, we don't know every detail of how gravity works, why do you assume that the one thing we know for certain is that it's a pull? 'Pull' is an entirely valid description of what happens as far as comprehension goes, the same way 'attracted' is to describe magnetism: but that doesn't mean it's physically true, no one proposes magnets feel randy. So not only are you wildly contradictory on yet another count, but you have nothing in support of anything you've said.
Even if your argument against pull-forces is true (something you've offered nothing in support of, save insistence), you can't apply it to gravity until you concede that we know some rather fundamental facts about it: such as the very 'what' you're saying we don't know.
Take, for example, your bell jar case. You say a pump pushes air out. How, exactly, can that be modeled as a push? Does the pump reach out to hug the air molecules, and push from the other side? Does it whisper to get more distant molecules to come closer, and push more that way? Even if we suppose your expanding bubble-air, how exactly can something be drawn closer without going to the other side and pushing?
You don't even need a bell jar. Purse your lips and breathe in. Real impressive 'pushing' of air then.
The real losers are those who are so arrogant to assume that they, and they alone, are able to part the veil and see everything clearly enough to do away with centuries of progress and corroboration and testing overnight.