It seems that there are many was to build with plain old dirt. Here’s a rough list in order of complexity:
This involves stacking wads of mud, conceptually as a wall — but in real life, choose your shape(s)!
Wattle & Daub
This involves shoving the mud into “Wattle” or arrays of sticks, mesh or mats. Old-style Tudor houses are built this way.
It adds the complexity of building a Wattle framework, but is a lot simpler to keep aligned than Cob (if you care).
This involves shoving mud into block forms, letting it dry a bit, turning each mud block onto its side, letting it dry a lot more, stacking the blocks on carefully chosen mud and letting it all dry.
This involves hammering nearly-dry mud into rectangular forms, letting it dry, then moving the forms up a little & repeating the action.
Doors & Windows
Doors & windows are generally made out of metal and/or wood & can be interesting forms all by themselves rather than mere bland rectangles. They can swing, tilt, fold, anything which works for you.
Well, it can be a lot cheaper than brick-&-tile but there is typically a lot more labour involved — you are, after all, standing in for the builders.
You get to express your creativity quite directly & at your own pace, but not all councils will see everything the way you want them to.
You can more easily suit the building to the site, weather or neighbourhood themes. Adding things like flue-heated beds & baths, small rooms & odd shapes is much easier if you do it yourself.