The role of ants in building soil.

I live in Wisconsin. I am told that we don't have earthworms native to Wisconsin, they were imported by European colonizers. We do have some very fertile soils. I'm curious which species did the things gardeners depend on earthworms to do.
Every autumn I stockpile many cubic yards of leaves. I build hugels with them during the summer. I often find colonies of tiny black ants in the leaves, especially oak leaves. And these oak leaves get turned into something that looks like peat moss in about a year. I have never tested my humus, but it works very well in lawn care applications. It also grows a bunch of squash and potatoes.
Can anyone tell me about the other critters in my soil? The ones I can see without a microscope.

When I see ants digging down into my rock-hard clay, I think they must be doing some good. I leave them alone.

They seem to be bringing particles of sand into my piles of leafmold.

I am not sure that ants have a role in soil building.  They might help with aeration, though.

Here is what Dr. Bryant Redhawk says:

Bryant said, "If ants come, they are good indicators that there is moisture in the soil and they do great at pulling organic materials into the soil, creating air ways (that also hold rain water) and they usually fertilize with their dead bodies as well.

https://permies.com/t/118927/Soil-building-plants-tough-conditions#964724

Bryant said, "I love this and I like ants, as long as they aren't where I don't want them to be. (when that happens I encourage them to move by spreading spent coffee grounds over their nesting area).

https://permies.com/t/115233/Mother-Nature-Soil-Tilling-Methods

I agree with the current replies but I wanted to add one more action that ants contribute to.

Ants 'plant' seeds by dragging them into their burrows to store/eat them. In some cases, these seeds will sprout and grow!

Kind of a fun seemingly unintentional effect of ants habits.

I've been annoyed at ants farming aphids.

Maybe pillbugs? I took a quick look around, this article suggests so, and mentions that some ants do eat decaying matter.

While this study has a different focus, it states that millipedes break down decaying matter and indicates improved soil.

Thank you Jolylynn for the links to some articles. Not many people out there singing praises to the pillbugs and millipedes. I suspect they're much more important than we realize. Somebody was processing all the organic matter before worms were imported to my region. And doing it very nicely. I notice many creatures in my piles. I'm trying to learn how they interact. They all have a place. I think variety in macroscopic organisms is just as important as the microorganisms. Don't love it when rodents get in the pile, but I love hearing the owls at night.