If the force of gravity were to change, slightly or not, there would be a variety of consequences. Most of them do not appear to be as
apocalyptic as you imagine. On an atomic or molecular level, gravity is not significant. It really only comes into play in the large-scale
structure of things.

If the force weakened slightly, the sun would get a little larger and cooler but there still would be the balance between fusion and gravity
preserving stars. The earth would be a little more distant from the sun but likely would remain habitable. Galaxies would be get larger, which may slow the spreading of heavy elements, leading to smaller or fewer rocky planets. Galactic clusters would be spread out more but this would likely have little impact.

If the force strengthened slightly, we'd see the opposite effects.

BTW: the ruler you mentioned would be 28 billion light years across. The universe is approximately 14 billion years old, which gives the maximum distance a signal could travel at the speed of light as 14 billion light years. This is the radius of the observable universe, not the diameter.

Adjusting the force of gravity by one inch in even a single light year would have no impact. You'd need to make a really large change to create havoc. There are some physical constants that require fine tuning relative to one another to allow matter to exist, but none require the extreme tuning you describe.

It is also rather egocentric to imagine that humans are the only intelligent creatures in the universe. Even on earth, our intelligence
often differs from other species by degree, not by kind. With 100 billion stars in our galaxy and 100 billion galaxies in the observable
universe, the odds of us being the only "intelligent" life are rather slim.

The difference between scientists and mullahs is that scientists observe the universe and test their understanding of how it works.  Mullahs act on their belief of how things should work and never test that belief. If you want to convince a scientist of something, just show them the evidence. If you want to convince a Mullah of something, good luck.

However, if you want scientists to respond to every crackpot "theory" someone dreams up, you are going to be disappointed. Scientists are no different than you or me. They have work to do and lives to live. And there are a lot more crackpots than scientists.

Einstein studied at some of the finest universities in Europe then spent years working out his theories before presenting them for publication. He had to show that they agreed with all known observations and made predictions that differed from previous theories. Those predictions had to be confirmed before his theories were accepted.

He didn't just come up with an idea that he thought might explain something in a religious text and expect the world to marvel at his
ingenuity.