There are two more sections of the murals not shown and they seem to be the most interesting for two reasons. The first is that we arent shown them and the second is that in that scene, while Steven marvels are the floating pyrmaid in the center of the room, Pearl(with Amethyst yawning beside her) is looking in the same direction the murals we're not shown/get a partial glimpse of.
There's one more thing I want to address that ties into multiple things I noticed.
If those things are people or if they're gems behind and infront of Rose, what is on top of that pyramid of people? At first I thought it was just a mountain, but notice how it looks almost like crystal? Notice how there's one behind Rose's opponent and glimpses of them can be seen of what little we do see of the two murals on the opposite side?
Now, notice how it looks like the people are either holding it up, hiding inside it or inside it, as if power it, as if they're fueling a gem weapon or a gem booster? Why? Well again, the same looking gem is shown behind the opponent and the other murals. It looks as if the gems are used to amplify its user or they're powers, examples of this can be seen in how the opponent is possibly using it to create all those floating diamonds, while Rose is possibly using it to use whatever power against the opponent.
Now those two abilities could be separate from those gems amplifiers themselves, but this is where I bring in the other murals.
Firstly: notice in the glimpse we seem on the opposite side mural on the left. It looks as if the sun or moon is charging it. Its then followed by a mural of what looks like one of the diamonds (or fused diamonds, which I'll get to in a second,) using or demonstrating their amplified powers or wipe out a lot of the crystal gems or to reinforce loyalty of gems on their side and gain loyalty from gems of Rose's side.
Now after those two murals we're on the big central mural which shows both sides using the gem amplifiers. Look at it, we can see both are standing under sunlight or the full moon (which is important later,) and both look large. Now we know diamonds a larger your average gem, and so are quartz gems, but what if the gem amplifiers also made the gems grow in mass? It would explain why the weapons at strawberry field are so large and it would explain why Rose is depicted as the same size as her opponent if they're arent just figuratively depicted that size, granted we dont necessary know Rose is fighting a diamond, after all that's a triangle on the opponent's chest. However whoever it is, they are either defeated by Rose or they fuse and then something happens in the final mural, but what?
Well this is where the moon/sun comes into play, I think that's whats fueling the gems, not people(I already gave that away, but whatever,) I think the mural was created by white diamonds forces to make it look like humans or gems were the fuel, but they discovered shorting after getting to earth that the sun/moon could power gems, which is the real reason the diamond base was on the moon, not just to overwatch the earth.
Though the murals are not just to make it look like the crystal gem use the humans as fuel, its to divert from the fact the sun or moon is the real fuel. Also it looks like there's an eclipse in the last mural, so maybe that's how the crystal gems got the upper hand and was the reason they released whatever wiped out/corrupted all the other crystal gems.
Alternatively the sun/moon looking thing is actually the geode or something like the geode and is used as a power source and nuke for gems and gem amplifiers, tho maybe the moon is also like the geode or cluster.... Im just spitballing at this point.