Organic matter, being light and fluffy, floats to the top while the mineral part of the soil sinks to the bottom of the jar. Sand, the largest and heaviest of the mineral portion of soil will settle on the bottom while any silt, the next size and weight will settle in the middle, and any clay, the smallest and lightest of the mineral component, will settle on the top of the mineral portion. While you might be interested in the makeup of the soil the most important part of that test is the organic matter

From what I can see you have mostly sand, maybe some silt, and a bit of clay, with a little organic matter. If the soil put in measured 4 inches divide the amount of OM, on top, by 4 to get the percent of OM in that sample. maybe about 3 percent organic matter.

What I have posted here numerous times is,

1) Soil test for organic
matter. From that soil sample put enough of the rest to make a 4 inch level in
a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and
replace the lid, tightly. Shake the jar vigorously and then let it stand for 24
hours. Your soil will settle out according to soil particle size and weight.
For example, a good loam will have about 1-3/4 inch (about 45%) of sand on the
bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above
that, and about 1/4 inch (about 5%) of organic matter on the top.